Gas collecting apparatus

ABSTRACT

The present invention relates to a gas collecting system collecting an inspection objective gas, such as a toxic gas discharged into an ambient air, and particularly to a gas collecting system which can achieve down-sizing of the system and permit implementation of analysis of gas concentration of the inspection objective gas at high precision with simple operation.

TECHNICAL FIELD

The present invention relates to a gas collecting system or collectingan inspection objective gas, such as toxic gas or the like, dischargedinto ambient air, and analyzing concentration of the collectedinspection objective gas. More specifically, the invention relates to agas collecting system which can implement an analysis of gasconcentration of an inspection objective gas at high precision withsimple operation with achieving downsizing of the system.

BACKGROUND ART

In the recent years, in dwelling houses or so forth employing variousnewly developed building materials, such as laminated plywood and thelike, it has been pointed out that toxic gas of volatile organiccompound, such as formic aldehyde and the like, discharged from thenewly developed building materials, and such gas should have harmfulinfluence on a living environment. On the other hand, ammonia gasgenerated from a concrete or paint may promote degradation of exhibitsin art museums and museums, or may be a cause of generation of faultyproducts in a clean room, such as semiconductor manufacturing factoriesand so forth. Therefore, demand for collection of the toxic gas in theambient air and analysis of gas concentration, is getting stronger. Forproviding a measure for such problem of toxic gas, it has been quiteimportant to measure a concentration of toxic gas component in theambient air, to investigation of a gas generation source and to know adischarge speed of the gas.

As a method for collecting an inspection objective gas, such as toxicgas or the like, a method to condensingly collect a fine amount of gashas been employed, in which a gas collecting system is constructed witha collecting vessel filled with a collecting liquid, an air pump, adrying agent, a flowmeter, a volume flowmeter (integrating flowmeter)and so forth. In an inspection site, an ambient air is introduced intothe collecting liquid with measuring a suction amount to continuouslycause bubbling by the ambient air in the collecting liquid to dissolvethe inspection objective gas in the ambient air into the solution forcondensing collection. Then, by analysis of the collecting liquid by achemical method to dissolve a gas component in the solution is derivedto convert into a concentration in the sucked ambient air.

On the other hand, by JIS (Japanese Industrial Standard) A 5908"particle board", there has been defined a method for measuring adischarge amount of formic aldehyde discharged from a wooden buildingmaterials. The method is to introduce a material to be inspected withcutting into a narrow paper tablet like piece into a glass desciccatortogether with distilled water contained in a tray, to leave for apredetermined period to naturally dissolve formic aldehyde into thedistilled water for collection.

However, in the former gas collecting system, it becomes necessary toappropriately control a gas flow rate (flow velocity) for making a gascollection rate constant to read variation of indicia of a gas volumeterwith measuring a period by a stop watch, or to frequently adjust a flowvelocity by a needle valve with connecting an instantaneous flowmeter.Therefore, in the conventional gas collecting system, it issignificantly troublesome for adjustment of flow rate or reading of agas suction amount. In conjunction therewith, the gas volumeter isprecision mechanical equipment, and thus is required sufficientattention in handing for expensiveness and sufficient level of skill.Also, an equipment and material for collection becomes large scale tocause difficulty in transportation of the equipment and material and inmovement among inspection sites to make it troublesome for installationand adjustment to make gas collecting operation cumbersome.

On the other hand, in the later method, by inspecting the distilledwater, in which formic aldehyde is collected, a gas discharge amount pera unit period can be predicted. However, in this method, it is requiredto cut a testing piece from the material to be inspected. Therefore, itis not possible to perform inspection for the building completelyconstructed to limit range of application.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a gas collectingsystem which can implement analysis of gas concentration of aninspection objective gas at high precision with simple operation, withachieving downsizing of the system.

A gas collecting system, according to the present invention, comprises aportable air pump which is driven by a portable battery to suck a gas inan inspection objective space, a collection vessel, in which acollecting liquid for collecting an inspection objective gas from thegas is filled, an induction passage having one end connected to thecollection vessel and the other end communicated with the inspectionobjective space for introducing the gas into the collection vessel, asuction passage having one end connected to the collection vessel andthe other end connected to a suction port of the air pump forintroducing the gas in the collection vessel into the air pump, anaccumulation body connected to a discharge port of the air pump,accumulating the gas discharged from the air pump and serving as avolumeter, drying means disposed between the accumulation body and thecollection vessel for drying the gas, a pressure switch detecting aninternal pressure of the accumulation body, a bypass passage connectingthe accumulation body to the suction port of the air pump bypassing thecollection vessel, and switching means for switching a flow pathconnecting the accumulation body to either one of the discharge port ofthe air pump and the bypass passage, and in conjunction therewith,connecting the discharge port of the air pump to an ambient air openingpassage when the accumulation body is connected to the bypass passage.

On the other hand, the system includes a main receptacle box and anauxiliary receptacle box mounted on the main receptacle box, the mainreceptacle box receives the air pump and the battery therein and hasmounting surfaces for mounting the drying means and the collectionvessel, the auxiliary receptacle box receives the switching means andthe pressure switch therein, and has a mounting portion for detachablymounting the accumulation body.

The accumulation body is a foldable and exchangeable bag.

The bag is a vinyl bag.

The collection vessel is formed with transparent material to be used asa color comparison tube, and is also used as a reaction tube to befilled with reagents reacting with the inspection objective gas.

The pressure switch detects an internal pressure of the accumulationbody reaching a predetermined pressure to output a stop signal for theair pump.

The pressure switch is connected among the air pump, a buzzer and apower source supplying operation power to the air pump and the buzzer,the pressure switch being constructed with a bag-formed extending membercommunicated with the accumulation body and causing expanding andcontracting deformation by a pressure of the gas introduced from theaccumulation body, a cylindrical guide surrounding the extending memberto guide the extending member in expanding direction, and a switch mainbody being provided in opposition to the extending member in expandingdirection thereof and being depressed by the expanding member forselectively establishing connection between a common terminal and eitherone of two switching terminals, wherein, each of the switching terminalsis connected to the buzzer and the air pump, respectively, and thecommon terminal is connected to the power source, and when an internalpressure of the accumulation body is reached to a predeterminedpressure, the connection with the common terminal is switched from theswitching terminal of the air pump to the switching terminal of thebuzzer by the extending member expanded in response thereto.

At least one of the induction passage and the suction passage has acapillary portion.

The collection vessel is formed into a cylindrical shape and its openingportion is closed by a cap, and the induction passage and the suctionpassage has an injection needle form tube portion, respectively, thesetube portions being inserted into the collection vessel through the cap.

At least a portion of the cap covering the opening portion of thecollection vessel is coated with an insulation layer of a material notinfluencing the collecting liquid.

The injection needle form tube portion is closed at a tip end thereofand is formed with a laterally oriented communication opening in thevicinity of the tip end portion.

The switching means is connected to a speed adjusting switch controllingdriving speed of the air pump by varying a supply voltage to the airpump from the battery in response to switching operation of the flowpath, when the discharge port of the air pump is connected to theaccumulation body, the air pump is driven at low speed, and when thebypass passage is connected to the accumulation body, the air pump isdriven at high speed.

A check valve is provided on the upstream side of the suction port ofthe air pump to only allow the gas flow to the suction port.

A given amount of 2N-NaOH solution as the collecting liquid is filled inthe collection vessel, after passing a given amount of the gascontaining the inspection objective gas, a given amount of AHMT reagentprepared by using HClO₄ as the reagents is filled within the collectionvessel to leave for a given period, and in conjunction with, anindication value is adjusted to a predetermined value by setting astandard color solution in an absorptiometer, then, a given amount ofKIO₄ reagent as said reagents is added into the collection vessel, andthen, the collection vessel is set in the absorptiometer for detectingconcentration of formic aldehyde from the indication value thereof.

A given amount of 2N-KOH solution as the collecting liquid is filled inthe collection vessel, after passing a given amount of the gascontaining the inspection objective gas, a given amount of AHMT reagentas the reagents is filled within the collection vessel to leave for agiven period, and in conjunction with, an indication value is adjustedto a predetermined value by setting a standard color solution in anabsorptiometer, then, a given amount of KIO₄ reagent as the reagents isadded into the collection vessel, and then the collection vessel is setin the absorptiometer for detecting concentration of formic aldehydefrom the indication value thereof.

On the other hand, a gas collecting system, according to the presentinvention, comprises a portable air pump which is driven by a portablebattery to suck a gas in an inspection objective space, a collectionvessel, in which a collecting liquid for collecting an inspectionobjective gas from the gas is filled, an induction passage having oneend connected to the collection vessel and the other end communicatedwith the inspection objective space for introducing the gas into thecollection vessel, a suction passage having one end connected to thecollection vessel and the other end connected to a suction port of theair pump for introducing the gas in the collection vessel into the airpump, an accumulation body connected to a discharge port of the airpump, accumulating the gas discharged from the air pump and serving as avolumeter, drying means disposed between the accumulation body and thecollection vessel for drying the gas, a pressure switch detecting aninternal pressure of the accumulation body, a bypass passage connectingthe accumulation body to the suction port of the air pump bypassing thecollection vessel, switching means for switching a flow path connectingthe accumulation body to either one of the discharge port of the airpump and the bypass passage, and in conjunction therewith, connectingthe discharge port of the air pump to an ambient air opening passagewhen the accumulation body is connected to the bypass passage, a mainreceptacle box receiving the air pump and the battery therein and havingmounting surfaces for mounting the drying means and the collectionvessel, and an auxiliary receptacle box mounted on the main receptaclebox, receiving the switching means and the pressure switch therein, andhaving a mounting portion for detachably mounting the accumulation body,wherein, the collection vessel is formed of a transparent material to beused as a color comparison tube, and is also used as a reaction tubefilled with reagents reacting with the inspection objective gas, thepressure switch detects an internal pressure of the accumulation bodyreaching a predetermined pressure for outputting a stop signal of theair pump, and the accumulation body is a foldable and exchangeable bag.

In the gas collecting system according to the present inventionconstructed as set forth above, mainly, the gas in the inspectionobjective space is taken into the collection vessel by driving the airpump to pass the gas through the collection liquid of the collectionvessel. Thereafter, the gas is sucked into the air pump through thedrying means, and the gas discharged from the air pump is accumulated inthe accumulation body to permit the accumulation body as volumeter.

On the other hand, for the inspection objective gas collected by thecollection liquid of the collection vessel, inspection can be performedby using the collection vessel as the reaction tube and the colorcomparison tube. Therefore, transfer of the collection liquid anddividing of a part of the collection liquid for analysis becomeunnecessary to improve operability in chemical analysis.

Furthermore, after completion of collection in one time, by varying flowpath of the switching means, the gas within the accumulation body isautomatically discharged from the ambient air opening passage withsucking by the air pump to enable preparation for next collection aftermaking the accumulation body empty. Accordingly, the gas collectingsystem can be simplified in construction, significantly, inexpensive andcompact, and can be operated easily without requiring skill.

On the other hand, by associating the pressure switch of theaccumulation body with the air pump, the air pump can be stoppedautomatically at a time when the internal pressure of the accumulationbody reaches the predetermined pressure. Therefore, collecting operationcan be automatically terminated and gas suction management complicatesand requiring skill as in the prior art, become unnecessary.

Furthermore, the opening portion of the collection vessel is closed bythe cap, the induction passage introducing the gas into the collectionvessel and the suction passage introducing the gas into the air pump areformed with the injection needle tube portions with the capillaryportions. Since these tube portions are mounted through the cap, settingand exchanging of the collection vessel is quite easy. Also, since thecapillary portion of the induction passage can also serve as aresistance tube of the gas flow, stabilization of the gas flow rate canbe achieved to enable enhancement of precision in inspection.

On the other hand, since at least the portion of the cap covering theopening portion of the collection vessel is covered with the insulationlayer, penetration of gas component generated from the cap into thecollection vessel can be prevented by the insulation layer. Therefore,even when the collection liquid is preliminarily filled in thecollection vessel, influence of gas component generated by the cap forthe collection liquid can be avoided. Therefore, the collection vesselcan be stored for a long period in the condition where the collectionliquid is preliminarily filled.

Accordingly, upon performing gas analysis by the gas collecting system,analyzing operation can be done easily and quickly only by setting thecollection vessel preliminarily filled with the collection liquid. Also,storage ability of the collection vessel filled with the collectionliquid can be significantly improved. Therefore, large amount ofcollection vessels containing the collection liquid can be produced atonce. In comparison with the case where the collection vessel and thecollection liquid are soled separately, the collection vessel containingthe collection liquid can be traded as a product. Furthermore, even whena large amount of collection vessels in which the collection liquidfills system is stocked, a blank value can be stable to improveprecision in analysis. Furthermore, since the cap does not affect forthe collecting liquid, inexpensive material can be used as the materialfor the cap.

On the other hand, the pressure switch is disposed between the buzzerand air pump, and the power source to control ON/OFF of actuation of thebuzzer and the air pump. When the inside of the accumulation body isfilled with a given amount of gas, driving of the air pump isautomatically stopped to stop sucking of the gas. Simultaneously, thebuzzer is actuated to notice this to permit to construct the gascollecting system to be convenient to use and permit accuratemeasurement.

Particularly, the pressure switch is designed to selectively connect thecommon terminal of the switch body with switching terminals by expansionof the extending member introduced the gas pressure. Thus, constructionbecomes simple to permit downsizing to facilitate assembling of thesystem to lower cost to permit manufacturing at low cost. On the otherhand, since expansion of the extending member can be guided by theguide, detection can be assured even when the gas pressure is small toachieve high performance.

On the other hand, the system may further comprises a casing coveringthe inspection objective space in a sealing condition from outside toenclose the inspection objective gas discharged from an inspectionobject enclosed therein, a sampling port provided with the casing, andconnected to the induction passage for introducing the gas containingthe inspection objective gas in the casing into the collection vessel, asupply port provided with the casing for supplying a reference gas intothe casing depending upon suction of the gas in the casing by the airpump, and a capillary passage disposed between the sampling port and theaccumulation body for lowering flow velocity of the gas sucked.

The capillary passage is disposed between the sampling port and thecollection vessel.

A filter is connected to the supply port, and the reference gas is anambient air purified by the filter.

A reference gas receptacle body filled with the reference gas isconnected to the supply port, and the reference gas is supplied to thecasing from the reference gas receptacle body.

Also, a gas collecting system, according to the present invention,comprises a casing covering an inspection objective space in a sealingcondition from outside to enclose an inspection objective gas dischargedfrom an inspection object enclosed therein, a sampling port providedwith the casing to sample a gas containing the inspection objective gasin the casing, an air pump sucking the gas from the inspection objectivespace in the casing, a supply port provided with the casing forsupplying a reference gas into the casing depending upon suction of thegas in the casing by the air pump, a collection vessel, in which acollection liquid for collecting the inspection objective gas from thegas is filled, an induction passage having one end connected to thecollection vessel and the other end connected to the sampling port forintroducing the gas into the collection vessel, a suction passage havingone end connected to the collection vessel and the other end connectedto a suction port of the air pump for introducing the gas in thecollection vessel into the air pump, an accumulation body connected to adischarge port of the air pump, accumulating the gas discharged from theair pump and serving as a volumeter, a capillary passage disposedbetween the sampling port and the accumulation body for lowering flowvelocity of the gas sucked, drying means disposed between theaccumulation body and the collection vessel for drying the gas;

a pressure switch detecting an internal pressure of the accumulationbody;

a bypass passage connecting the accumulation body to the suction port ofthe air pump bypassing the collection vessel; and

switching means for switching a flow path connecting the accumulationbody to either one of the discharge port of the air pump and the bypasspassage, and in conjunction therewith, connecting the discharge port ofthe air pump to an ambient air opening passage when the accumulationbody is connected to the bypass passage, wherein, the casing has anopening in a bottom portion, on which a packing for fitting the casingwith the inspection object in gas-tight fashion is provided, a filter isconnected to the supply port, and the reference gas is an ambient airpurified by the filter.

In the gas collecting system according to the present inventionconstructed as set forth above, by abutting the casing onto the surfaceof the inspection object, the interior in the casing becomes sealedcondition to enclose the inspection objective gas discharged from theinspection object. Then, the inspection objective gas collected withinthe casing is mixed with the reference gas introduced through the supplyport and supplied to the collection vessel through the sampling port.Accordingly, in the collection vessel, detection can be performed byseparating the inspection objective gas mixed to the reference gas.Thus, the gas discharge amount per unit period of the inspection objectto be inspected can be easily detected.

On the other hand, since the casing is formed the opening in the bottomportion, and the packing is mounted on the peripheral edge of theopening, the interior of the casing can be sealed condition by thepacking on the peripheral edge of the opening by fitting the opening ofthe casing in gas-tight fashion on the inspection object, such as theexisting floor, wall and so forth when the inspection object cannot becut as the test piece, such as the floor, the wall or so forth of theexisting building. Therefore,even from the floor and the wall, theinspection objective gas can be sampled. Thus, not only for materialinspection before construction, but also for the existing building afterconstruction, the gas discharge amount can be easily measured atarbitrary position. Also, even if the inspection object is constructedby composing different kinds of materials, measurement in the actuallyconstructed condition becomes possible, and inspection of the gasdischarge amount per unit area discharged from individual material inthe constructed building becomes possible to be useful for study of gasdischarge phenomenon.

On the other hand, since the capillary passage is provided in thesampling port to adjust flow velocity of the gas, in which theinspection objective gas is admixed excessive lowering of pressure inthe casing when the gas within the casing is sucked through the samplingport. Accordingly, penetration of the ambient air into the casingthrough the peripheral edge of the opening of the casing can avoided,and in addition, forced discharge of the inspection objective gas fromthe inspection object by excessively lowering of pressure can be avoidedto enhance precision of inspection.

Also, the system may further comprises a casing covering the inspectionobjective space in a sealing condition from outside to enclose theinspection objective gas discharged from an inspection object enclosedtherein, a sampling port provided with the casing, and connected to theinduction passage for introducing the gas containing the inspectionobjective gas in the casing into the collection vessel, an internalpressure maintaining bag provided in the casing and having expandabilityand sealing ability, and a pressure induction passage connected to theinternal pressure maintaining bag through the casing and introducing apressure adjusting gas for expanding the internal pressure maintainingbag according to lowering of the internal pressure of the casing.

The casing has an opening in a bottom portion, and a packing for fittingthe casing with the inspection object in gas-tight fashion is providedon the opening.

The casing is a chamber receiving a material piece to be inspected asthe inspection object.

The casing is formed of a transparent material.

A stirring means is provided in the casing and the stirring means stirsthe gas in the casing.

The pressure adjusting gas is introduced through the pressure inductionpassage into the internal pressure maintaining bag by a pressurereduction in the casing.

A port opening and closing means is disposed between the sampling portand the induction passage for opening and closing therebetween, and apressure introducing means for opening and closing the pressureintroducing passage is provided therewith.

Furthermore, the system may includes a volume varying bag provided inthe casing and having expandability and sealing ability, and a gassupplying and discharging passage connected to the volume varying bagthrough the casing, for supplying and discharging a volume adjusting gasto the volume varying bag to vary volume in the casing by expanding anddeflating the volume varying bag.

At least either one of the internal pressure maintaining bag and thevolume varying bag is disposed in plural in the casing.

An opening and closing means for the gas supplying and dischargingpassage is provided therewith.

An adjusting gas receptacle body filled with the pressure adjusting gasor the volume adjusting gas is connected to at least either one of thepressure induction passage and the gas supplying and dischargingpassage, and these gas are supplied from the adjusting gas receptaclebody.

Furthermore, a gas collecting system, according to the presentinvention, comprises a casing covering an inspection objective space ina sealing condition from outside to enclose an inspection objective gasdischarged from an inspection object enclosed therein, a sampling portprovided with the casing to sample a gas containing the inspectionobjective gas in the casing, an air pump sucking the gas from theinspection objective space in the casing, a collection vessel filledwith a collecting liquid for collecting the inspection objective gasfrom the gas, an induction passage having one end connected to thecollection vessel and the other end connected to the sampling port forintroducing the gas into the collection vessel, a suction passage havingone end connected to the collection vessel and the other end connectedto a suction port of the air pump for introducing the gas in thecollection vessel into the air pump, an accumulation body connected to adischarge port of the air pump, accumulating the gas discharged from theair pump and serving as a volumeter, drying means disposed between theaccumulation body and the collection vessel for drying the gas, apressure switch detecting an internal pressure of the accumulation body,a bypass passage connecting the accumulation body to the suction port ofthe air pump bypassing the collection vessel, switching means forswitching a flow path connecting the accumulation body to either one ofthe discharge port of the air pump and the bypass passage, and inconjunction therewith, connecting the discharge port of the air pump toan ambient air opening passage when the accumulation body is connectedto the bypass passage, an internal pressure maintaining bag provided inthe casing and having expandability and sealing ability, a pressureinduction passage connected to the internal pressure maintaining bagthrough the casing and introducing a pressure adjusting gas forexpanding the internal pressure maintaining bag according to lowering ofthe internal pressure of the casing, a volume varying bag provided inthe casing and having expandability and sealing ability, and a gassupplying and discharging passage connected to the volume varying bagthrough the casing, for supplying and discharging a volume adjusting gasto the volume varying bag for varying volume in the casing by expandingand deflecting the volume varying bag.

In the gas collecting system according to the present inventionconstructed as set forth above, the expandable internal pressuremaintaining bag in the casing covering the inspection object in thesealed condition is provided to make it possible to introduce thepressure adjusting gas within the internal pressure maintaining bag.Therefore, when a given amount of gas is sampled within the casing formeasuring concentration of the inspection objective gas, the pressure inthe casing in the sealed condition can be lowered depending upon thesampling amount. However, since the pressure adjusting gas is introducedinto the pressure maintaining bag in a volume corresponding to thesampling amount due to pressure reduction effect, to cause expansion tomaintain the gas pressure within the casing constant.

On the other hand, by the internal pressure maintaining bag havingsealing ability, the pressure adjusting gas is not mixed with the gascontaining the inspection objective gas within the casing and thus, theinspection objective gas to be sampled may not be diluted. Accordingly,by making the concentration of the inspection objective gas higher, theprecision of inspection can be improved.

On the other hand, since the lowering of the pressure within the casingcan be avoided, the gas generation amount from the inspection object maynot be increased by the pressure reducing effect, and the casing is notrequired high pressure resistive sealing ability.

Also, since the volume varying bag is provided in addition to theforegoing internal pressure maintaining bag, the net volume of thecasing can be varied without providing many kinds of casing of differentvolumes by preliminarily expanding the volume varying bag within thecasing. Therefore, when the released amount of the inspection objectivegas from the inspection object is small and gas concentration in thecasing cannot reach the concentration, at which measurement is possibleunless leaving for a long period, high concentration of the gas can beestablished within a short period even when gas discharge amount issmall by adjusting the net volume of the casing smaller by expanding thevolume variable bag. Also, even when the gas is sampled from the casingof the reduced net volume, the internal pressure maintaining bag on theother hand is expanded following to taking out of the gas from thecasing to permit to maintain the gas pressure within the casingconstant.

Furthermore, a gas collecting system, according to the presentinvention, comprises a casing covering an inspection objective space ina sealing condition from outside to enclose an inspection objective gasdischarged from an inspection object enclosed therein, a pair of gascirculating ports provided with the casing and circulating a gas throughthe casing, an air pump sucking the gas containing the inspectionobjective gas from the inspection objective space in the casing, acollection vessel, in which a collection liquid collecting theinspection objective gas from the gas is filled, an induction passagehaving one end connected to the collection vessel and the other endconnected to one of the gas circulating ports of the casing forintroducing the gas into the collection vessel, a suction passage havingone end connected to the collection vessel and the other end connectedto a suction port of the air pump for introducing the gas in thecollection vessel into the air pump, a buffer disposed between adischarge port of the air pump and the other of the gas circulatingports of the casing to buffer a gas pressure by temporarily storing thegas discharged from the air pump, and in conjunction therewith, tocirculate the gas to the casing again, and humidity adjusting meansdisposed between the buffer and the collection vessel for adjusting ahumidity of the gas circulated to be constant.

The casing has an opening in a bottom portion, and a packing for fittingthe casing with the inspection object in gas-tight fashion is providedon the opening.

The casing is a chamber receiving a material piece to be inspected asthe inspection object.

The casing is formed of a transparent material.

The buffer is a bag to be expanded and deflected depending upon adifference between a pressure of the gas stored therein and an ambientair pressure.

The humidity adjusting means is a container filled with a humidityadjusting liquid adjusting humidity of the gas.

The humidity adjusting liquid is a salt solution.

The collection vessel is provided in plural and in parallel, andswitching device disposed between the collection vessels and one of thegas circulating ports of the casing to selectively communicate thecasing with either one of the collection vessels.

The switching device switches the communication between the respectivecollection vessels and the casing according to an elapsed time.

The switching device is controlled the switching operation by means of atimer.

The air pump is portable and is driven by a portable battery.

The collection vessel is formed with transparent material to be used asa color comparison tube, and is also used as a reaction tube to befilled with reagents reacting with the inspection objective gas.

The collection vessel is formed into a cylindrical shape and its openingportion is closed by a cap, and the induction passage and the suctionpassage having an injection needle form tube portion, respectively,these tube portions being inserted into the collection vessel throughthe cap.

The cap is coated with an insulation layer of a material not influencingthe collecting liquid at least at a portion covering the opening portionof the collection vessel.

A given amount of 2N-NaOH solution as the collecting liquid is filled inthe collection vessel, after passing a given amount of the gascontaining the inspection objective gas, a given amount of AHMT reagentprepared by using HClO₄ as the reagents is filled within the collectionvessel to leave for a given period, and in conjunction therewith, anindication value is adjusted to a predetermined value by setting astandard color solution in an absorptiometer, then, a given amount ofKIO₄ reagent as the reagents is added into the collection vessel, andthen, the collection vessel is set in the absorptiometer for detectingconcentration of formic aldehyde from the indication value thereof.

A given amount of 2N-KOH solution as the collecting liquid is filled inthe collection vessel, after passing a given amount of the gascontaining the inspection objective gas, a given amount of AHMT reagentas the reagents is filled within the collection vessel to leave for agiven period, and in conjunction with, an indication value is adjustedto a predetermined value by setting a standard color solution in anabsorptiometer, then, a given amount of KIO₄ reagent as the reagents isadded into the collection vessel, and then, the collection vessel is setin the absorptiometer for detecting concentration of formic aldehydefrom the indication value thereof.

On the other hand, a gas collecting system, according to the presentinvention, comprises a casing covering an inspection objective space ina sealing condition from outside to enclose an inspection objective gasdischarged from an inspection object enclosed therein, a pair of gascirculating ports provided with the casing to circulate a gas throughthe casing, an air pump sucking the gas containing the inspectionobjective gas from the inspection objective space in the casing, acollection vessel filled with a collection liquid for collecting theinspection objective gas from the gas, an induction passage having oneend connected to the collection vessel and the other end connected toone of the gas circulating ports of the casing for introducing the gasinto the collection vessel, a suction passage having one end connectedto the collection vessel and the other end connected to a suction portof the air pump for introducing the gas in the collection vessel intothe air pump, a buffer disposed between a discharge port of the air pumpand the other of the gas circulating ports of the casing to buffer a gaspressure by temporarily storing the gas discharged from the air pump,and in conjunction therewith, to supply the gas to the casing again, andhumidity adjusting means disposed between the buffer and the collectionvessel for adjusting a humidity of the gas circulated to be constant,wherein, the casing has an opening in a bottom portion, on which apacking for fitting the casing with the inspection object in gas-tightfashion is provided, the collection vessel is formed with transparentmaterial to be used as a color comparison tube, and is also used as areaction tube to be filled with reagents reacting with the inspectionobjective gas, the buffer is a bag to be expanded and deflecteddepending upon a difference between a pressure of the gas stored thereinand an ambient air pressure, and the humidity adjusting means is acontainer filled with a humidity adjusting liquid prepared by a saltsolution for adjusting humidity of the gas.

Furthermore, a gas collecting system, according to the presentinvention, also comprises a casing covering an inspection objectivespace in a sealing condition from outside to enclose an inspectionobjective gas discharged from an inspection object enclosed therein, apair of gas circulating ports provided with the casing and circulating agas through the casing, an air pump sucking the gas containing theinspection objective gas from the inspection objective space in thecasing, a collection vessel filled with a collection liquid collectingthe inspection objective gas from the gas, an induction passage havingone end connected to the collection vessel and the other end connectedto one of the gas circulating ports of the casing for introducing thegas into the collection vessel, a suction passage having one endconnected to the collection vessel and the other end connected to asuction port of the air pump for introducing the gas in the collectionvessel into the air pump, a buffer disposed between a discharge port ofthe air pump and the other of the gas circulating ports of the casing tobuffer a gas pressure by temporarily storing the gas discharged from theair pump, and in conjunction therewith, to circulate the gas to thecasing again, and humidity adjusting means disposed between the bufferand the collection vessel for adjusting a humidity of the gas circulatedto be constant, wherein the casing has an opening in a bottom portion,on which a packing for fitting the casing with the inspection object ingas-tight fashion is provided, the buffer is a bag to be expanded anddeflected depending upon a difference between a pressure of the gasstored therein and an ambient air pressure, the humidity adjusting meansis a container filled with a humidity adjusting liquid prepared by asalt solution for adjusting humidity of said gas, the collection vesselis provided in plural and in parallel, the collection vessels beingformed with transparent material to be used as a color comparison tube,and being also used as a reaction tube to be filled with reagentsreacting with the inspection objective gas, and switching device isdisposed between the collection vessels and one of the gas circulatingports of the casing to selectively communicate the casing with eitherone of the collection vessels according to time counted.

In the gas collecting system according to the present inventionconstructed as set forth above, by simply fitting the casing on theinspection object and driving the air pump, the gas is circulatedthrough the casing. In conjunction therewith, the inspection objectivegas collected within the enclosed casing is taken into the collectionvessel. The gas is sucked from the collection vessel and accumulatedwithin the buffer. The gas again returned into the casing is purified asthe inspection objective gas is collected in the collection vessel andthe humidity thereof is maintained constant by the humidity adjustingmeans. After performing collection of the inspection objective gas bycirculating the gas within the closed loop circuit for a predeterminedperiod, the quantitative analysis of the inspection objective gas may beperformed by the collection vessel. Thus, the inspection objective gascan be collected without damaging the inspection object. By this, notonly inspection for the construction material as independent materialbut also at the arbitrary position in the use condition of the material,namely in the building after construction, the inspection objective gascan be sampled to permit inspection of the material. At this time,adjustment or so forth of the system upon collection is unnecessary tosimplify handing to require no skill. Also, the gas collecting operationand gas measurement can be performed at arbitrary position to beinspected.

Also, since the gas can be circulated within the closed loop withoutcausing variation of pressure by the buffer, error in measurement can beavoided with simple construction.

On the other hand, by providing a plurality of collection vessels andswitching connection of the collection vessels with the casing perpreliminarily set collection period, gas collection according to timecounted becomes possible to monitor variation of the discharge amount ofthe inspection objective gas according to the elapsed time.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram of an entire circuit of the first embodimentof a gas collecting system according to the present invention;

FIG. 2 is an explanatory illustration of a switching cock to be providedin the gas collecting system shown in FIG. 1;

FIG. 3 is a perspective view showing an assembled condition of the gascollecting system shown in FIG. 1;

FIG. 4 is an enlarged section of a cap to be employed in an impinger ofthe gas collecting system according to the present invention;

FIG. 5 is a graph comparing the storing condition of a collecting liquidfilled in the impinger for a case of a normal cap and a case of the capshown in FIG. 4;

FIG. 6 is an enlarged section of the major part showing a modificationof the cap of FIG. 4;

FIG. 7 is a circuit diagram of a pressure switch to be employed in thegas collecting system according to the present invention;

FIG. 8 is a section showing a construction of the pressure switch shownin FIG. 7;

FIG. 9 is a section showing an operating condition of the pressureswitch shown in FIG. 7;

FIG. 10 is a diagrammatic illustration of a push-type switch body to beprovided in the pressure switch shown in FIG. 7;

FIG. 11 is a perspective view showing a characteristic part of thesecond embodiment of the gas collecting system according to the presentinvention;

FIG. 12 is a graph showing a relationship between a length of acapillary tube to be employed in the gas collecting system shown in FIG.11 and a flow rate;

FIG. 13 is an illustration showing a characteristic part of the thirdembodiment of the gas collecting system according to the presentinvention;

FIG. 14 is an illustration of a general construction showing amodification of the gas collecting system shown in FIG. 13;

FIG. 15 is an illustration of a general construction showing anothermodification of the gas collecting system shown in FIG. 13;

FIG. 16 is a circuit diagram of an entire circuit showing the fourthembodiment of the gas collecting system according to the presentinvention; and

FIG. 17 is a circuit diagram of an entire circuit showing a modificationof the gas collecting system shown in FIG. 16.

BEST MODE FOR CARRYING OUT OF THE INVENTION

The preferred embodiments of the present invention will be discussedhereinafter in detail with reference to the accompanying drawings.

The first embodiment of a gas collecting system according to the presentinvention basically includes a portable air pump 12 which is driven by aportable battery to suck a gas in an inspection objective space, animpinger 14 as a collecting vessel, in which a collecting liquid 28 forcollecting an inspection objective gas from the foregoing gas is filled,a tube 24 having one end connected to the impinger 14 and the other endcommunicated with the foregoing inspection objective space for servingas an induction flow passage for introducing the foregoing gas into theimpinger 14, a tube 26 having one end connected to the foregoingimpinger 14 and the other end connected to a suction port 12a of theforegoing air pump 12 for serving as a suction flow passage introducingthe foregoing gas into the air pump 12, a bag 18 connected to adischarge port 12b of the air pump 12 and accumulating the foregoing gasdischarged from the air pump 12 for serving as a storage body operatingas a volumeter, a drying agent tube 16 disposed between the bag 18 andthe impinger 14 and serving as drying means for drying the foregoinggas, a pressure switch 30 detecting an internal pressure of theforegoing bag 18, a tube 36 as a bypass passage connecting the foregoingbag 18 to the foregoing suction port 12a of the foregoing air pump 12bypassing the foregoing impinger 14, a switching cock 34 serving asswitching means for switching a flow passage connecting the foregoingbag 18 to either one of the foregoing discharge port 12b and theforegoing tube 36, and, in conjunction therewith, connecting thedischarge port 12b of the air pump 12 to an ambient air communicationpassage 38 when the bag 18 is connected to the tube 36, a mainreceptacle box 40 receiving the foregoing air pump 12 and the foregoingbattery therein, and in conjunction therewith, having mounting surfaces40a and 40b on the outer surface for mounting the foregoing drying agenttube 16 and the foregoing impinger 14, and an auxiliary receptacle box42 mounted on the main receptacle box 40, receiving the foregoingswitching cock 34 and the foregoing pressure switch 30 therein andhaving a mounting portion 46 for detachably mounting the foregoing bag18. The impinger 14 is formed of a transparent material and to be usedas a color comparison tube, and also as a reaction tube to be filledreagents reacting with the inspection objective gas. On the other hand,the pressure switch 30 detects the internal pressure of the bag 18reaching the predetermined pressure to output a stop signal of the airpump 12. Also, the bag 18 is foldable and exchangeable.

Discussing in detail, the shown embodiment of the gas collecting system10 is a type sucking the ambient air, and includes the portable air pump12 as shown in FIG. 1. By sucking the ambient air in the inspectionobjective space with the air pump 12, the inspection objective gas inthe ambient air is taken. The foregoing air pump 12 is portable asdriven by a not shown portable battery, such as a dry cell or the like.In the suction port 12a of the air pump 12, the impinger 14 and thedrying agent tube 16 also used as a filter, are provided in sequentialorder. Also, in the discharge port 12b of the air pump 12, the bag 18accumulating the gas discharged from the discharge port 12b is provided.The bag 18 is used as volumeter measuring a gas amount. On the otherhand, on the downstream side of the drying agent tube 16, a check valve20 permitting only flow of gas in a direction toward the suction port12a of the air pump 12 is provided.

The impinger 14 is formed by a bottomed cylindrical glass tube in a testtube like configuration, in which an opening portion on the upper end isclosed by an elastic cap 22. In the impinger 14, the tube 24 forintroducing an ambient air and the tube 26 connecting the interior ofthe impinger 14 to the suction port 12a are provided. These tubes 24 and26 are formed by metallic capillaries of injection needle form. Then,the tubes 24 and 26 formed by metallic capillaries are pierced into theelastic cap 22 to insert respective needle shaped tip end portions 24aand 26a into the impinger 14. On the other hand, in the impinger 14, apredetermined amount of the collecting liquid 28 is filled. The tip endportion 24a of the tube 24 is dipped into the collecting liquid 28, andin conjunction therewith, the tip end portion 26a of the tube 26 islocated above the liquid surface of the collecting liquid 28.

The pressure switch 30 is provided between the air pump 12 and the bag18. The pressure within the bag 18 is detected by the pressure switch30. At a timing, at which the bag 18 is filled with the air, the airpump 12 is stopped.

On the other hand, on the downstream side of the pressure switch 30, theswitching cock 34 is provided in the discharge tube 32 communicated withthe bag 18. The switching cock 34 connects the bag 18 to the dischargetube 32 of the air pump 12 at the normal position shown in FIG. 2(a),and the bag 18 to the tube 36 bypassing the impinger 14 at the switchedposition shown in FIG. 2(b). At the switched position of the switchingcock 34, the discharge pipe 32 is communicated with the ambient aircommunication passage 38.

The gas collecting system 10 constructed as set forth above, isassembled as a compact construction as shown in FIG. 3. Namely, on theside surface 40a on the near side of the main receptacle box 40receiving the air pump 12 and the dry cell or so forth to be the drivingsource, the auxiliary receptacle box 42 receiving the switching cock 34,the pressure switch 30 and so forth, is mounted with occupyingapproximately half of the space. On the side surface 42a on the nearside of the auxiliary receptacle box 42, a lever 44 of the switchingcock 34 is projected. On the other hand, on the side surface 42b on theside, a mounting portion 46 of the bag 18 is provided. On the otherhand, on the side surface 40b on the side of the main receptacle box 40,two drying agent tubes 16 are mounted. Also, on the side surface 40a onthe near side of the main receptacle box 40, the impinger 14 is mountedat the position on the side of the auxiliary receptacle box 42. Forexample, the gas collecting system is formed in a size having 10 cm ofdepth, 12 cm of width and 18 cm of height.

In the shown embodiment of the gas collecting system 10 constructed asset forth above, by driving the air pump 12, the ambient air in themeasuring site is introduced into the impinger 14 through the tube 24 topass the collecting liquid 28 in the impinger 14 with bubbling thelatter, and then sucked into the air pump 12 through the drying agenttube 16. The gas discharged from the air pump 12 is accumulated in thebag 18. Then, by using the bag 18 as the volumeter, the pressure switch30 is actuated at a timing where the bag is filled to stop the air pump12 to complete collecting operation of the inspection objective gas. Atthis timing, the inspection objective gas in the ambient air is admixedwith the collecting liquid 28 of the impinger 14 to perform inspectionwith taking the impinger 14 as the reaction vessel and the colorcomparison tube.

After completion of one cycle of collecting operation, by setting theswitching cock 34 at the switched position shown in FIG. 2(b), the bag18 is connected to the suction port 12a of the air pump 12 so that thegas in the bag 18 is sucked by the air pump 12 to be dischargedautomatically to make the bag empty for preparation to the nextcollection.

Thus, in the shown embodiment, the bag 18 is employed in place of thegas volumeter, and the bag 18 may be a container like a vinyl bag.Accordingly, the bag 18 can be transported in the folded condition andcan be quite light in weight. Also, the bag 18 can be externallyconnected, and the suction amount can be arbitrarily varied by varyingthe size of the bag 18.

On the other hand, the pressure switch 30 can be constructed with amicroswitch, a pressure receiving portion of rubber, a plastic tube andso forth. It is possible to construct that when the bag 18 is filledwith air and the air pressure in the bag 18 is slightly elevated, themicroswitch is operated by the pressure. Accordingly, since suctionamount per one time is determined to be constant depending upon thevolume of the bag 18, switching operation with reading the gas volumeteror with observing the scale as in the prior art becomes unnecessary.Therefore, while the gas volumeter is constructed as precisionmechanical equipment in the prior art, it is expensive and requiressufficient attention in handling. However, the shown embodiment does notrequire such attention at all. Also, as for the bag 18, various sizesare available in the market as the gas containers to be used for gasanalysis, they may be utilized with preliminarily measuring the volumesthereof.

On the other hand, in the gas collecting system 10, after completion ofcollection in one cycle, in order to prepare for next collection, itbecomes necessary to discharge the air in the bag 18. By switching theswitching cock 34 housed within the auxiliary receptacle box 42, theflow passage of the air pump 12 is reversed to automatically dischargethe gas within the bag 18 with maintaining the bag 18 in the mountedposition. Accordingly, operation ability and workability becomesuperior. Particularly, by forming the switching cock 34 as modifiedfour-way type with improving three-way cock of polyethylene, forexample, switching of the flow passage can be performed by one-touchoperation by one switching operation. On the other hand, the switchingcock 34 is associated with a not shown speed adjusting switch varyingthe drive voltage of the air pump 12 to be constructed so that the airpump 12 is driven at low speed upon collection of gas and at high speedupon discharging, associating with switching of the switching cock 34.

Here, a condensation rate of the gas component of the inspectionobjective gas in the collecting liquid 28 collected by the impinger 14is determined by a ratio of the collecting liquid amount and the suckedambient air amount. Since the impinger 14 is made compact, condensationand collection can be done by small amount (1 to 3 ml) of collectingliquid 28. Therefore, high condensation can be obtained with smallambient air suction amount, and the volume of the bag 18 can be madesmall to be 1 to 5 liters. On the other hand, upon color comparisonanalysis, since the impinger 14 can be used as the reaction vessel andcolor comparison tube as it is, it becomes unnecessary to transfer thecollecting liquid 28 or sample a part of the collecting liquid 28 foranalysis, and operability in chemical analysis is improved. Here, colorcomparison analysis means an analyzing method performed by adding areagent to a solution, in which the inspection objective gas iscollected, for indicating a particular color by chemical reactions tomeasure light transparency by color density and to measure concentrationof the gas component. On the other hand, in the impinger 14, small-sizeglass test tube available from the market can be used to make theimpinger 14 for facilitating handling at quite a low cost, in comparisonto the conventional impinger.

On the impinger 14, the elastic cap 22 is fitted, and large sizeinjection needle form metallic capillaries are employed for the tube 24and the tube 26 to be set to the elastic cap 22. These tube 24 and tube26 may certainly provide flow passages for the air by simply piercingthrough the elastic cap 22. Since the impinger may be operated in thecondition where the elastic cap 22 is maintained in the fittedcondition, the collecting liquid 28 will not spill even if the impinger14 is erroneously turned over. Also, the collecting liquid 28 and thereagents for reaction can be filled into the impinger 14 by an injectorwith maintaining the elastic cap 22 in the set condition, wherebyoperation ability and security can be improved. The tube 24 and the tube26 have small diameter by constructing as the capillaries so that bubbledischarged from the tip end of the tube 24 into the collecting liquid 28becomes smaller to enhance dissolving ability of the gas component andthus to improve collection efficiency.

Furthermore, upon releasing the tube 24 and the tube 26 after completionof collecting operation of the inspection objective gas, the interior ofthe impinger 14 is slightly lowered in pressure to suck the collectingliquid 28 residing within the tube 24 into the impinger 14. Therefore,washing of the tube 24 and tube 26 becomes unnecessary. Also,contamination by the residual liquid can be prevented. In addition, thetip ends of the tube 24 and the tube 26 are formed as closed needle tofacilitate insertion into the elastic cap 22. Communication openings forthe gas is formed as transverse holes in the vicinity of the tip endportion 24a and 26a to prevent plugging by chips of the rubber.

The tube 24 formed as metallic capillary may also serve as a resistancetube for the gas flow to stabilize gas flow rate. Therefore, gas flowrate (flow velocity) can be appropriately controlled to make collectionratio of the inspection objective gas uniform to improve precision ofinspection of the inspection objective gas. Also, by selecting lengthand thickness of the tube 24 and the tube 26, the flow velocity can becontrolled with little influence of performance of the air pump 12, andthus can be stabilized. Thus, monitoring by the instantaneous flowmeteror needle valve as was required in the prior art can be eliminated so asto permit collecting operation without paying attention for adjustmentof the flow rate. While the foregoing discloses the case where the tube24 and the tube 26 are formed as metallic capillaries, they are notspecified to the shown construction but can be glass or plasticcapillaries.

As set forth above, the shown embodiment of the gas collecting system 10has a simple construction, in which the impinger 14 and the drying agenttube 16 are provided in the suction port 12a of the portable air pump 12and the bag 18 is provided in the exhaust port 12b. Therefore, as shownin FIG. 3, respective of these components can be assembled into compactconstruction as a whole. Accordingly, the gas collecting system 10assembled as set forth above is portable to demonstrate superiortransporting ability and to make adjustment of assembling of thematerial and component unnecessary, thus permits simple collection ofair at an arbitrary site. Therefore, handling can be simplified torequire no skill, and permits anybody's use. In this case, by using withsetting on a tripod mount for camera or so forth, adjustment of heightcan be done easily, and the shown system requires less space.Accordingly, the gas collecting system is quite simple in constructionand is inexpensive and compact.

Here, the structure of the elastic cap 22 employed in the foregoingfirst embodiment will be discussed.

As shown in FIG. 4, the elastic cap 22 closing the upper end openingportion 14a of the impinger 14 is formed of a synthetic rubber. At leasta portion of the elastic cap 22 formed of the synthetic rubber, which isinserted into the impinger 14 with closing the upper end opening portion14a, is coated by an insulation layer 48 formed of a material notinfluencing the collecting liquid 28.

Namely, the elastic cap 22 is designed so that the bottom surface 22aand the substantially lower half of side surface 22b thereof is insertedinto the impinger 14. In order to cover the bottom surface 22a and theside surface 22b entirely, the insulation layer 48 is integrally coatedor adhered as a thin film layer. The insulation layer 48 is not limitedto the bottom surface 22a and the side surface 22b of the elastic cap 22but may coat the overall surfaces including the upper surface 22c, as amatter of course. The insulation layer 48 itself is selected so as notto influence the collecting liquid 28 and a soft material having anappropriate elasticity so as not to spoil sealing ability of the elasticcap 22. For example, resin materials, such as polyethylene, vinylidenechloride resin, fluoroplastic, vinyl chloride and the like or metalfoil, such as tin and the like may be used.

The elastic cap 22 of the impinger 14 which is also used as the colorcomparison tube, is coated the bottom surface 22a and the side surface22b, which is inserted into the upper surface opening portion 14a of theimpinger 14, with the insulation layer 48. Therefore, the gas componentgenerated from the elastic cap 22 is blocked from penetrating into theimpinger 14 by the insulation layer 48. Thus, even when the collectingliquid is preliminarily filled in the impinger 14 before implementationof analysis of the inspection objective gas, the gas component generatedin the elastic cap 22 does not influence the collecting liquid 28.Therefore, it has become possible to store for a long period in acondition where the collection liquid 28 is filled in the impinger 14.

FIG. 5 is a graph showing comparison of variation of concentration offormic aldehyde when the collecting liquid 28 is filled in the impingerto which the normal elastic cap is set, and the impinger 14 to which theshown embodiment of the elastic cap 22 having the insulative layer 48.Characteristics A shows the characteristics of the impinger closed onlyby the elastic cap, and characteristics B shows the characteristics ofthe shown embodiment, which the impinger 14 is closed by elastic cap 22with the insulation layer 48. Of course, the graph shows influence ofthe elastic cap to the collecting liquid 28 in the condition where gascollection is not performed.

Namely, as shown by the characteristics A, in the impinger, for whichthe insulation layer is not provided on the elastic cap, certain gascomponent generated from the elastic cap influences the collectingliquid 28 associating with elapsing of days to increase concentrationsubstantially proportional (about 0.04 ppm in eight days) as if formicaldehyde is sucked. On the other hand, in the shown embodiment of theimpinger 14 employing the elastic cap 22 with the insulation layer 48, apeak (about 0.0025 ppm) is reached after elapsing of six days withslight increase between three to eight days, but it is extinguishedafter elapsing of eight days as shown by the characteristics B. It canbe appreciated that the gas component generated from the elastic cap 22gives little influence for the collecting liquid 28.

Therefore, when the elastic cap 22 coated by the insulation layer 48 isemployed, it becomes possible to store for a long period in a conditionwhere the collecting liquid is filled in the impinger 14. Therefore,upon performing gas analysis, the impinger 14 containing preliminarilyprepared collecting liquid 28 is set on the gas collecting system 10. Bythis, analyzing operation can be significantly simplified and performedquickly. Also, since storage for long period becomes possible, itbecomes possible to trade in the condition where the collecting liquid28 is filled in the impinger 14 to significantly enhance a commercialvalue in comparison with the case where the impinger 14 and thecollecting liquid 28 are sold separately.

The insulation layer 48 is not limited to be coated or adhered, but canbe formed as an independent sheet as shown in FIG. 6. In this case, theinsulation layer 48a is formed into a size substantially covering thebottom surface 22a and the side surface 22b of the elastic cap 22 sothat, after covering the upper end opening portion 14a of the impinger14 by placing the center portion of the insulation layer 48a thereover,the elastic cap 22 is inserted into the upper end opening portion 14awith depressing the insulation layer 48a. Even with such construction,the portion of the elastic cap 22 to be inserted into the impinger 14 iscovered with the insulation layer 48a to isolate the elastic cap 22 fromthe interior of the impinger 14.

Next, the structure of the pressure switch 30 employed in the firstembodiment will be discussed in detail.

FIG. 7 shows the air pump 12 and the bag 18, and the periphery of theconnecting portion. The pressure switch 30 is connected to a branchportion 32a disposed between the air pump 12 and the bag 18 and extendedfrom an intermediate portion of the discharge tube 32 flowing the gasaccumulated within the bag 18 from the air pump 12, and is actuated upondetecting a pressure within the bag 18. On the other hand, a buzzer 50is provided on the gas collecting system 10. The pressure switch 30 isdisposed between the buzzer 50 and the air pump 12, and a power source52 supplying an operation power thereto for controlling ON/OFF actuationof the buzzer 50 and the air pump 12. Namely, a power source line 54extended from the power source 52, a buzzer side line 56 extended fromthe switch 30 and connected again to the power source via the buzzer 50and the air pump 12, and an air pump side line 58 are connected to thepressure switch 30 for electrically connecting and opening the buzzerside line 56 and the air pump side line 58 in respect of the powersource line 54.

As shown in FIGS. 8 and 9, the pressure switch 30 is mainly constructedwith an outer casing 60 formed into a hollow cylindrical shapedconfiguration and serving as a guide, an extending member 62 arranged inan upper portion within the outer casing 60, and a depression typeswitch body 64 arranged in a lower portion within the outer casing 60.

Here, the extending member 62 is a bag shaped receptacle body ofreversed bell shaped configuration expandably formed of a materialhaving flexibility, such as a rubber membrane, and can be formed, forexample, by a medical finger sac available in the market, and has areceptacle portion 62a which can sealingly receive the gas therein. Theperipheral edge portion of the upper end opening of the extending member62 is sealingly clamped and engaged between the upper opening endportion 60a and a rubber plug body 66 received with closing the sametherein. The gas induction pipe 68 is provided through the centerportion of the plug body 66. On the tip end portion of the gas inductionpipe 68, the branch pipe 32a of the discharge pipe 32 is connected toestablish communication between the receptacle portion 62a of theextending member 62 and the interior portion of the bag 18 forintroducing gas into the receptacle portion 62a of the extending member62. When the gas is not introduced into the receptacle portion 62a, theextending member 62 is placed in entirely flexed condition as shown inFIG. 8. When the gas is introduced into the receptacle portion 62a viathe gas induction pipe 68, the volume is increased to make the externalshape greater as shown in FIG. 9. Then, once the gas in the receptacleportion 62a is extinguished, it returns to the original flexedcondition.

On the other hand, the outer casing 60 is provided surrounding theperipheral side of the extending member 62. Namely, when the extendingmember 62 is expanded, the outer casing 60 restricts expansion of theextending member 62 with inner walls 60b from the side portion, and, inturn, permits expansion in the axial direction, here, downward. By this,the extending portion 62 is expanded with being guided toward the pushtype switch body 64 by the inner walls 60b of the outer casing 60. Onthe other hand, in the inner walls 60b of the outer casing 60, acommunication hole 70 for certainly providing communication with theoutside is formed so that the air between the outer casing 60 and theextending member 62 is introduced and discharged through thecommunication hole 70 depending upon expansion and contraction of theextending member 62.

On the other hand, the push type switch body 64 is fixed in the lowerportion on the inner side of the outer casing 60 via a rubber mountingmember 72 disposed on the inner periphery in tightly sealing position.The switch body 64 has an operating portion 74 provided on the innersurface of the outer casing 60 with directing toward the extendingmember 62 and two, three or more of terminals 76 provided in a positionexposed to the outside of the outer casing 60. The operating portion 74is urged outward from the switch body 64 by an urging member, such as anot shown spring housed within the switch body 64 to be depressed intothe switch body 64 when it is depressed, as shown in FIG. 9, and toreturn to the original position when depression is removed. Then,between the operating portion 74 and the extending member 62, anactuating member 78 is provided for transmitting an expansion force ofthe extending member 62 to the operating portion 74 of the switch body64. The actuating member 78 includes two upper and lower plate members78a and 78b connected via a hinge portion 78c and is constructedexpandably. The lower end portion of the actuating member 78 isconnected to the operating portion 74 of the switch body 64 in thevicinity thereof via a hinge portion 78d. On the other hand, the upperplate member 78a is provided in contact with the outer bottom surface ofthe extending member 62. Then, the actuating member 78 is presseddownward in the outer casing 60 via the hinge portion 78c by expansionof the extending member 62, and the lower plate member 78b contacts withthe operating portion 74 to depress the latter. On the other hand, uponcontraction of the extending member 62, the operating portion 74 isreleased from depression and is pushed outwardly by the urging force ofthe urging member housed within the switch body 64 to contact with thelower plate member 78b of the actuating member 78 to push the latter forextending the actuating member 78. By this, the extending member 62 isreturned in the contracting direction as becoming smaller in its outershape and returned to the original condition. Thus, the operatingportion 74 is either depressed or opened depending upon expansion andcontraction of the extending member 62.

Depending upon depression and release of the operating portion 74 as setforth above, the switch body 64 establishes and releases mutualelectrical connection of the respective terminals 76 of the switch body64. Namely, the switch construction of the switch body 64 has one commonterminal 76a in a plurality of terminals. For the common terminal 76a,either of the remaining terminals 76 is selectively connected as aswitching terminal 76b to form a changeover switch construction. Whenthe operating portion 74 is depressed, the one switching terminal 76b isconnected to the common terminal 76a, and the other is opened. On theother hand, when the operating portion 74 is opened, the other switchingterminal 76b is connected to the common terminal 76a and the oneswitching terminal is opened. As such switch body 64, a microswitchcommercially available is preferably employed, in general.

In the pressure switch 30, the common terminal 76a is connected to thepower source line 54, and the switching terminals 76b are respectivelyconnected to the buzzer side line 56 and the air pump side line 58 sothat when the extending member 62 is expanded by gas pressure,electrical communication between the air pump 12 and the power source 52is switched from the established condition to the opened condition, andthe electrical communication between the buzzer 50 and the power source52 is switched from the opened condition to the established condition.Accordingly, in the gas collecting system 10, when the interior of thebag 18 is filled with a given amount of air, driving of the air pump 12is automatically stopped to interrupt introduction of the ambient airfrom the inspection objective space. In conjunction therewith, thebuzzer 50 can be actuated to report this.

In such pressure switch 30, the operating portion 74 of the switch body64 is depressed by expansion of the extending member 62 to establish andopen the connections between two, three or more terminals 76. Therefore,construction is simple to easily achieve reduction in cost anddownsizing. On the other hand, since expansion of the extending member62 can be guided by the outer casing 60, when it is applied to the gascollecting system 10 set forth above, it can satisfactorily detect thepressure even when the pressure to be detected is low. Further, sincethe commercially available micro-switch is used as the switch body 64,high reliability can be obtained with certainly achieving highdurability. Also, by replacing the switch body 64 with other switchconstruction, switching function of the switch can be easily modified towiden application field and to achieve high general applicability. Thesetting of the pressure actuating the pressure switch 30 can be simplymodified by appropriately selecting the switch body 64 in view of theurging force of the urging member and so forth, for example.

By the way, while the shown embodiment employs the extending member 62formed into reversed bell shaped configuration, it can be of othershapes.

Next, the second embodiment of the gas collecting system according tothe present invention basically includes a casing 82 covering theinspection objective space in a sealing condition from the outside toenclose the inspection objective gas discharged from the inspectionobject 80 filled therein, a sampling port 84 provided in the casing 82for sampling the gas in the casing 82 containing the inspectionobjective gas, the air pump 12 sucking the gas within the casing 82containing the inspection objective gas, a supply port 86 provided inthe casing 82 for supplying a reference gas into the casing 82 inresponse to suction of the gas in the casing 82, the impinger 14 as thecollection vessel filled with the collecting liquid 28 for collectingthe inspection objective gas from the foregoing sampled gas, the tube 24as the induction passage connected to the impinger 14 at one end andconnected to the sampling port 84 at the other end for introducing thegas into the impinger 14, the tube 26 as the suction passage connectedto the impinger 14 at one end and the suction port 12a of the air pump12 at the other end for guiding the gas within the impinger 14 into theair pump 12, the bag 18 as a accumulating body serving as volumeter,connected to the discharge port 12b of the air pump 12, accumulating thegas discharged from the air pump 12, a capillary tube 88 as a capillaryflow passage provided between the sampling port 84 and the bag 18 forlowering flow velocity of the sucked gas, the drying agent tube 16provided between the bag 18 and the impinger 14 and serving as dryingmeans for drying the gas, the pressure switch 30 detecting the internalpressure of the bag 18, a tube 36 as a bypass passage connecting the bag18 to the suction port 12a of the air pump 12 bypassing the impinger 14,and the switching cock 34 serving as the switching means for switchingflow passage to connect the bag 18 to either the discharge port 12b ofthe air pump 12 or the tube 36 and connecting the discharge port 12b ofthe air pump 12 to the ambient air opening passage 38 when the bag 18 isconnected to the tube 36. The casing 82 has an opening 82a in its bottomportion. In the opening 82a, the packing 90 is provided for fitting thecasing 82 to the inspection object 80 in airtight fashion. A filter 92is connected to the supply port 86. The reference gas is the ambient airpurified by the filter 92.

The second embodiment is directed to a type for sucking the gas into thecasing 82 and simultaneously supplying the reference gas to theinspection object space sealed by the casing 82. While the constructionof the downstream side from the impinger 14 is similar to that of thefirst embodiment, the construction on the upstream side of the impinger14 is characteristic. Thus, only the characteristic portion isdiscussed.

As shown in FIG. 11, the shown embodiment of the gas collecting system10 includes the casing 82 formed in hemispherical form in apredetermined thickness with a transparent material. In the casing 82,the supply port 86 for taking the purified air as the reference gas intothe casing 82, and the sampling port 84 supplying the gas in the casing82, in which the inspection objective gas is admixed, into the gascollecting system 10 constructed as illustrated in FIG. 1, are providedin opposed positions. The air pump 12 is designed to forcedly suck thegas within the casing 82.

On the peripheral edge portion of the opening 82a of the casing 82, thepacking 90 formed of soft rubber or the like is mounted so that theopening 82a is depressed onto the surface of the inspection object 80via the packing 90. On the other hand, the capillary tube 88 woundedinto spiral form as a resistance tube is connected to the sampling port84. The flow velocity of the gas by suction of the air pump 12 isrestricted at low speed by the capillary tube 88.

Ambient air purified through a catalyst filled in the filter 92 isemployed as the purified air introduced into the casing 82 from thesupply port 86. In this case, the catalyst filled in the filter 92 maybe selected from activated charcoal, porous polymer beads, molecularsieve, chemical filter and so forth appropriately depending upon kind ofthe inspection objective gas. In FIG. 11, in place of the filter 92, abag 94 as a reference gas receptacle body filled with the purificationair employed in the reference gas or nitrogen gas or the like to be usedas the reference gas, may be employed, and the bag 94 may be connectedto the supply port 86 for introducing the reference gas in the bag 94into the casing 82.

With the construction set forth above, in the shown embodiment of thegas collecting system 10a, the opening 82 a of the casing 82 is urgedonto the inspecting portion of the inspection object 80 under thecondition where the capillary tube 88 connected to the sampling port 84of the casing 82 is connected to the tube 24 of FIG. 1, and inconjunction therewith, the filter 92 is connected to the supply port 86of the casing 82. At this time, on the opening 82a of the casing 82, thesoft packing 90 is provided. Therefore, upon urging the opening 82a ontothe surface of the inspection object 80, the opening 82a can be sealedby the packing 90. On the other hand, by forming the casing 82transparent, checking of the installation condition or observation ofthe condition of the surface of the inspection object 80 can be easilyachieved upon urging the casing 82 onto the inspection object 80.

Then, when the gas in the casing 82 is sucked from the sampling port 84by the air pump 12, the air purified by the filter 92 is introduced intothe casing 82 from the supply port 86, in the amount corresponding tothe sucked amount. At this time, the inspection objective gas dischargedfrom the inspection object 80 is collected in the enclosed casing 82.The collected inspection objective gas is admixed with the purified airintroduced from the supply port 86 and then sucked from the samplingport 84 by the air pump 12. Then, the gas sucked for a predeterminedperiod by the air pump 12 is accumulated in the bag 18. In conjunctiontherewith, inspection of the inspection objective gas contained in thecollected gas is quantitatively analyzed by a chemical method using theimpinger 14.

At this time, the discharge amount of the inspection objective gas fromthe portion covered by the casing 82 can be derived by the followingequation (1).

    (discharge amount of inspection objective gas)=(collected gas amount)/(opening area of casing×period of collecting operation)(1)

On the other hand, in the shown embodiment, since the capillary tube 88is connected to the sampling port 84 of the casing 82 to apply aresistance for the gas flow sucked from the interior of the casing 82into the air pump 12 and to restrict the flow velocity low, when the gaswithin the casing 82 is sucked from the sampling port 84, the excessivenegative pressure within the casing 82 can be prevented. Accordingly, itcan avoid occurrence of penetration of the ambient air into the casing82 through the sealed position, despite of the fact that the packing 90is provided on the peripheral edge of the opening 82a of the casing 82for sealing. Further, it also becomes possible to prevent the inspectionobjective gas from being forcedly discharged by the penetrating ambientair to enhance precision of analysis.

The capillary 88 may stably and arbitrarily set the flow velocity of theair at low speed by appropriately selecting the internal diameter andthe length of the tube as shown in FIG. 12. FIG. 12 shows a result ofmeasurement of relationship between the length and the flow rate in thecase where a tube formed of polytetrafluorocarbone (tradename: Teflon)is used as the capillary tube 88.

While the foregoing embodiment shows the case where the capillary tube88 is connected to the sampling port 84, its construction is notspecified to this. If the inspection objective gas may be absorbed intothe inner surface of the capillary tube 88 to cause a measurement error,the capillary tube 88 may be connected on the downstream side of the airpump 12.

Accordingly, the shown embodiment of the gas collecting system 10a canperform inspection by collecting the inspection objective gas by simplypressing the casing 82 onto the surface of the inspection object 80.Therefore, it becomes unnecessary to cut a test piece from theinspection object 80. Therefore, not only for material inspection beforeconstruction, the inspection objective gas discharge amount can beeasily measured at an arbitrary position even for the existing buildingafter construction.

Further, many construction materials often include different kinds ofmaterials in combination. For example, in case of combination where afinishing material is fixed on the concrete by applying a bonding agent,measurement becomes possible even after construction is completed.Therefore, it is quite useful in studying a gas discharging phenomenon.Furthermore, though measurement of the toxic gas in the building is onlydone as an average concentration in a large space in the prior art, itbecomes possible to inspect gas amount per unit area as discharged fromeach individual material, thus facilitating the study for a measurepreventing toxic gas generation according to the present gas collectingsystem 10a.

Discussion has been made for the case where the filter 92 is connectedto the supply port 86 of the casing 82 to introduce the purified ambientair into the casing 82. However, when a bag 94 is used in place of thefilter 92, the gas in the bag 94 is introduced into the casing 82associating with suction of the gas from the sampling port 84.

In the foregoing embodiment, though discussion has been given for thecase where the casing 82 is pressed onto the inspection object 80, it ispossible to form the casing 82 as a closed box-shaped chamber to receivean inspection test piece and to collect gas discharged therefrom.

Further, by providing a stirring means within the casing 82 if required,it becomes possible to stir the gas containing the inspection objectivegas within the casing 82 by the stirring means.

Next, the third embodiment of the gas collecting system according to thepresent invention is basically constructed with a casing 96 covering theinspection objective space from the outside in a sealed condition toenclose the inspection objective gas discharged from the inspectionobject 80 enclosed therein, a sampling port 98 provided in the casing 96and sampling the gas containing the inspection objective gas within thecasing 96, the air pump 12 sucking the gas from the inspection objectivespace within the casing 96, the impinger 14 as the collecting vesselfilled with the collecting liquid 28 for collecting the inspectionobjective gas from the foregoing gas, the tube 24 connected to theimpinger 14 at one end and to the sampling port 98 at the other end andserving as an induction passage for introducing the gas into theimpinger 14, the tube 26 connected to the impinger 14 at one end and theinduction port 12a of the air pump 12 at the other end and serving asthe suction passage introducing the gas in the impinger 14 into the airpump 12, the bag 18 as an accumulation body serving as a volumeter,connected to the discharge port 12b of the air pump 12 and accumulatingthe gas discharged from the air pump 12, the drying agent tube 16provided between the bag 18 and the impinger 14 and serving as thedrying means for drying the gas, the pressure switch 30 detecting theinternal pressure of the bag 18, the tube 36 serving as the bypasspassage connecting the bag 18 to the suction port 12a of the air pump 12bypassing the impinger 14, the switching cock 34 serving as theswitching means for switching the passage so as to connect the bag 18 toeither the discharge port 12b of the air pump 12 or the tube 36 and toconnect the discharge portion 12b of the air pump 12 to the ambient airopening passage 38 when the bag 18 is connected to the tube 36, a firstenvelope 100 serving as an internal pressure maintaining bag providedwithin the casing-96 and being sealingly expandable, a tube 102connected to the first envelope 100 by extending through the casing 96and serving as a pressure introducing passage for introducing a pressureadjusting gas for expanding the first envelope 100 according to loweringof the internal pressure of the casing 96, a second envelope 104provided in the casing 96 and sealingly expandable for serving as avolume varying bag, and a tube 106 connected to the second envelope 104by extending through the casing 96, and serving as a gas introducing anddischarging passage for supplying and discharging the volume adjustinggas to the second envelope 104 for modifying the volume within thecasing 96 by expanding and contracting the second envelope 104.

The third embodiment is the type that the gas within the casing 96 issucked with maintaining the gas pressure within the inspection objectivespace closed by the casing 96. Similarly to the second embodiment, inthe shown embodiment, while the construction on the downstream side ofthe impinger 14 is the same as that of the first embodiment, theconstruction on the upstream side of the impinger 14 is characteristic.Therefore, discussion will be given only for the characteristic portion.

For simplification of disclosure, first, FIG. 13 shows the case, inwhich only first envelope 100 is provided, and FIG. 14 shows the casewhere the second envelope 104 is additionally used.

As shown in FIG. 13, the shown embodiment of the gas collecting system10b has the casing 96 for collecting the inspection objective gasdischarged from the inspection object 80 by covering the inspectionobject 80 in the gas-tight condition. The gas containing the inspectionobjective gas, within the casing 96 is supplied to the gas collectingsystem constructed as shown in FIG. 1 to perform analysis of theinspection objective gas in the gas.

The casing 96 is constructed as a chamber of a closed structure as shownin FIG. 13, so that the inspection object 80, such as a plywood piece orthe like, as the inspection material piece, is housed within the casing96 as a form of chamber. The sampling port 98 for the interior gas isprovided in the casing 96. An opening and closing cock 108 as a portopening and closing means is provided in the sampling port 98. Thesampling port 98 is connected to the impinger 14 of the gas collectingsystem 10 via the tube 24. Within the casing 96, the expandable firstenvelope 100 is provided. Into the first envelope 100, ambient airoutside of the casing is freely introduced via a tube 102.

The first envelope 100 is preferably formed with a flexible thin filmhaving high flexibility so that a resistance is significantly small,when the first envelope 100 is expanded. Then, the tube 102 communicatedwith the first envelope 100 is sealingly mounted through an upper plateof the casing 96 so that the ambient air may be introduced freely intothe first envelope 100 by maintaining a cock 110 open, which serves as apressure introducing opening and closing means of the tube 102. On theside surface in the casing 96, a stirrer 112 as stirring means ismounted at a portion not causing interference with the first envelope100 when it is expanded. By the stirrer 112, the gas in the casing 96 isstirred to be uniformly mixed with the discharged inspection objectivegas.

The collecting operation of the inspection objective gas by the gascollecting system 10b is similar to that of the first embodiment. Thegas in the casing 96 is sucked by the air pump 12 and the inspectionobjective gas in the gas is collected by the impinger 14. In conjunctiontherewith, the gas discharged from the air pump 12 is accumulated in thebag 18 serving as a volumeter.

Particularly, in the shown embodiment, a released amount of theinspection objective gas is derived as follow. After first gas samplingby the gas collecting system 10b, a predetermined elapsed time ismeasured. After the predetermined period, next gas sampling and gasconcentration measurement is performed to derive the released amount ofthe inspection objective gas by the following equation (2).

    Q={C2 (Vo-Vs)-C1·Vo}(1/T)                         (2)

where

Q: gas generation amount from material E to be inspected;

C1: first gas concentration measured value;

C2: second gas concentration after elapsing a period T;

Vo: gas volume of casing before first sampling;

Vs: sampling amount;

T: elapsed period to second sampling from first sampling.

Further, by repeating concentration measurement by gas sampling perarbitrary elapsed time, it also becomes possible to perform long termobservation of variation in gas concentration and variation in gasgeneration amount in the casing according to the elapsed time.

On the other hand, in the shown embodiment of the gas collecting system10b, the closed casing 96 is employed for collecting the inspectionobjective gas discharged from the inspection object 80, and theexpandable first envelope 100 is provided within the casing 96 to permitintroduction of the ambient air outside of the casing 96 into the firstenvelope 100. Accordingly, the inspection objective gas discharged fromthe inspection object 80 is enclosed within the casing 96. Theinspection objective gas is increased according to elapsed time andconcentration of the inspection objective gas within the casing 96 isincreased.

Then, upon measurement of gas concentration, the air pump 12 is actuatedby opening the opening and closing cock 108 of the sampling port 98. Thegas containing the inspection objective gas within the casing 96 is thensucked into the impinger 14 through the sampling port 98. At this time,the pressure in the casing 96 in a closed condition is lowered dependingupon suction amount of the gas. Then, by this pressure reduction, thefirst envelope 100 is expanded by introduction of the ambient air for avolume corresponding to the suction amount through the tube 102.Therefore, the pressure reduction amount in the interior of the casing96 can be canceled by the expansion amount of the first envelope 100 tomaintain the gas pressure within the casing 96 constant. At this time,the ambient air introduced from the outside is maintained within thefirst envelope 100 and is not mixed with the gas within the casing 96.Therefore, the inspection objective gas to be sampled will not bediluted. Accordingly, the concentration of the sampled inspectionobjective gas can be made high enough to permit significant improvementin precision in measurement upon gas analysis.

Further, since lowering of pressure within the casing 96 can beprevented, various defects to be caused by pressure reduction can beavoided. Namely, amount of the inspection objective gas to be dischargedfrom the inspection object 80 can be increased by pressure reduction tomake gas concentration higher than the normal state. However, in theshown embodiment, this promotion of discharging of the inspectionobjective gas is avoided to eliminate error in the gas concentration tobe analyzed. Furthermore, considering pressure reducing function,significantly high pressure resistive sealing ability would be requiredfor the casing 96. However, since the pressure reduction is not causedin the shown embodiment, it becomes unnecessary to increase strength ofthe casing 96 and to pay attention to sealing ability of the same. Whilethe shown embodiment has been disclosed for the case where a singlefirst envelope 100 is provided within the casing 96, it is possible toprovide a plurality of first envelopes 100.

FIG. 14 shows a modification for the foregoing third embodiment, inwhich the same components to those in the third embodiment will beidentified by the same reference numerals and redundant discussion willbe omitted.

The shown modification of the gas collecting system 10b is provided twoenvelopes 100 and 104 within the casing 96, in which the first envelope100 serves as an internal pressure maintaining bag, and the other secondenvelope 104 is used as a volume varying bag. The first envelope 100 isadapted to maintain the internal pressure within the casing 96 constantas shown in the third embodiment, in which when the gas within thecasing 96 is sucked by the air pump 12 through the sampling port 98 uponstarting of gas collecting operation, the ambient air is introduced fromoutside of the casing 96 into the first envelope 100 according tolowering of the gas pressure within the casing 96.

On the other hand, the second envelope 104 is used by closing the cock114 as the opening and closing means for supplying and discharging gas,in a condition, where the air is preliminarily introduced through thetube 106 for expansion within the casing 96 before initiation of gascollecting operation. By maintaining the second envelope 104 in theexpanded state, the actual volume within the casing 96 can be varied.

Accordingly, in the modification, when the released amount of theinspection objective gas from the inspection object 80 is small and thegas concentration in the casing 96 cannot reach the level enablingmeasurement unless leaving it for a long period, the second envelope 104is expanded to make the net volume smaller. Even when the dischargeamount of the inspection objective gas is small, high concentration gascan be generated in the casing 96 within a short period of time.

As set forth above, by providing the second envelope 104, the net volumein the casing 96 can be varied without varying size of the casing 96itself. Therefore, troublesomeness for preparing a plurality kinds ofcasings 96 with different volumes and to exchange them as required, canbe avoided.

Then, by making the net volume smaller using the second envelope 104,even when the inspection objective gas within the casing 96 is sampled,the ambient air outside of the casing 96 can be freely introduced intothe first envelope 100 according to suction of the gas within the casing96, and the gas pressure within the casing 96 can be maintained constantby expansion of the first envelope 100.

On the other hand, while the shown embodiment employed the one firstenvelope 100 and the one second envelope 104, respectively, the presentinvention is not limited to the embodiment and respective envelopes canbe provided in plural.

FIG. 15 shows a further modification of the third embodiment, in whichthe same components to those of the third embodiment will be identifiedby the same reference numerals and redundant discussion will be omitted.

The modified gas collecting system 10b of the present embodiment isconstructed such that the casing 96 is formed into a cover shapedconfiguration, in which the bottom portion is opened, and the packing116 is mounted on the peripheral edge of the opening 96a.

Accordingly, in the shown modification, when the inspection object 80cannot be cut as the test piece, such as the floor and wall of theexisting building, the opening 96a of the casing 96 can maintain theinterior of the casing 96 in an air-tight condition via the packing 116of the peripheral edge of the opening 96a by fitting the opening 96a ofthe casing 96 onto the inspection object 80, such as existing floor andwall, in the air-tight fashion. Therefore, the inspection objective gasdischarged from the floor or wall within the casing 96 may be collected,and the inspection objective gas collected within the casing 96 can beanalyzed by the gas collecting system 10 shown in FIG. 1.

Further, in the shown modification, there is shown the case where thefirst envelope 100 for maintaining the gas pressure is providedsimilarly to the casing 96 of the chamber shape shown in the firstembodiment (see FIG. 13). However, it should not be taken limitative,and it is possible to apply the first envelope 100 and the secondenvelope 104 similarly to the foregoing modification (see FIG. 14).

In the third embodiment and the modifications thereof, there is shown acase where the ambient air is introduced into the first envelope 100 andthe second envelope 104 as the gas. However, the gas to be introduced isnot specified to the ambient air. It is also possible to connect therespective tubes 102 and 106 to an adjusting gas receptacle body, suchas a bomb filled with dedicated pressure adjusting gas or volumeadjusting gas through tubes and to supply the dedicated gas enclosedwithin the receptacle body to the respective envelopes 100 and 104through the respective tubes 102 and 106. On the other hand, as the gasto be filled in the casing 96, such gases must be selected that does notreact with the inspection objective gas discharged from the inspectionobject 80.

Further, by forming the casing 96 with a transparent material, itbecomes possible to check the setting condition of the inspection object80 and to observe the condition of the surface of the inspection object80.

The fourth embodiment of the gas collecting system according to thepresent invention basically includes a casing 118 covering theinspection objective space from outside and to enclose the inspectionobjective gas discharged from the inspection object 80 filled therein, apair of gas circulating ports 120 and 122 provided in the casing 118 andfor circulating the gas to the casing 118, an air pump 124 sucking thegas containing the inspection objective gas from the inspectionobjective space within the casing 118, an impinger 128 serving as acollecting vessel and filled with a collecting liquid 126 for collectingthe inspection objective gas from the gas, a tube 130 connected to theimpinger 128 at one end and to one of the gas circulating ports 120 ofthe casing 118 at the other end and serving as an induction flow passagefor introducing the gas into the impinger 128, a tube 132 connected tothe impinger 128 at one end and to a suction port 124a of the air pump124 at the other end for serving as a suction flow passage introducingthe gas within the impinger 128 into the air pump 124, a buffer 134provided between the discharge port 124b of the air pump 124 and theother of the gas circulating port 122 of the casing 118 to buffer thegas pressure by temporarily accumulating the gas discharged from the airpump 124 and circulating and supplying the gas to the casing 118 again,and a humidity adjusting means provided between the buffer 134 and theimpinger 128 for adjusting humidity of the circulated gas constant. Thecasing 118 has an opening 118a in the bottom portion. A packing 138 forfitting the casing 118 to the inspection object 80 in gas-tight fashion,is provided on the opening 118a. The buffer 134 is a bag capable ofbeing expanded and contracted depending upon a difference between thepressure of the gas accumulated therein and the ambient pressure. Thehumidity adjusting means is a humidity conditioner bottle 136 filledwith a humidity conditioner 140 prepared with a salt solution foradjusting humidity of the gas. The impinger 128 is formed with atransparent material for serving as a color comparison tube and also asa reaction tube, to which reagent reacting with the inspection objectivegas is filled, and is provided in plural and in parallel relationship.Between the impinger 128 and one of the gas circulating port 120 of thecasing 118, an electromagnetic valve 142 serving as switching means forselectively switching the connection between a plurality of impingers128 and the casing 118 according to the elapsed time.

The fourth embodiment is the type that the gas in the inspectionobjective space enclosed by the casing 96 is circulated within a closedloop circuit for collecting the inspection objective gas.

For simplification of discussion, a case where one impinger 128 isemployed, illustrated in FIG. 16, and FIG. 17, shows the case where aplurality of impingers 128 are selectively switched by theelectromagnetic valves 142.

As shown in FIG. 16, the shown embodiment of the gas collecting system10c has the casing 118 formed into a hemisphere shape with apredetermined thickness from a transparent material for collecting theinspection objective gas naturally discharged from the inspectingportion. Around the casing 118, the impinger 128, the air pump 124, thehumidity conditioner bottle 136 and the buffer 134 are connected insequential order to form a closed flow passage for circulating the gasso that the gas in the casing 118 is forcedly sucked and circulated bythe air pump 124, and the inspection objective gas is collected in theimpinger 128.

In the casing 118, the gas circulating port 122 for taking thecirculating gas and the gas circulating port 120 feeding the gas, inwhich the inspection objective gas is admixed, from the casing 118, areprovided in opposed positions. On the peripheral edge of the opening118a of the casing 118, the packing 138 formed of soft rubber or thelike, is mounted. The packing 138 is pressed onto the surface of theinspection object 80 to sealingly enclose the interior of the casing118.

The impinger 128, the tube 130 introducing gas thereinto, and the tube132 thus feeding out the gas are similar to the impinger 14, the tubes24 and 26 in the first embodiment. The portion of the cap of theimpinger 128 covering the opening portion of the impinger 128 is alsocoated by the insulation layer of the material which does not influencethe collecting liquid 126.

The air pump 124 is portable and driven by the battery, such as drycells or the like, which is also similar to the first embodiment. Thesuction port 124a is connected to the impinger 128 via the tube 132, andthe discharge port 124b is connected to the humidity conditioner bottle136.

The humidity conditioner bottle 136 is formed by a cylindrical glassbottle. The upper end opening portion is closed by a rubber cap. Apredetermined amount of the humidity conditioner 140, which is a saltsolution, is filled into the humidity conditioner bottle 136. The tipend of a tube 144 introducing the gas is extended into the liquid of thehumidity conditioner 140. The tip end of a tube 146 discharging the gasis extended above the liquid surface of the humidity conditioner 140,and bubbling of the introduced gas is carried out. The tube 144 isconnected to the discharge port 124b of the air pump 124, and the tube146 is connected to an induction opening 148 of the buffer 134 tomaintain the humidity of the gas which is circulated to the casing 118.Namely, as the humidity conditioner 140, for example, a saturatedsolution of BaCl₂.2H₂ O which is a salt solution can be used. By passingair through the saturated solution at 24.5° C., air containing 88% ofhumidity is obtained, and the humidity of the passing air is maintainedat a predetermined value. This is because the humidity of air in contactwith the salt solution becomes constant in relation to the water vaporpressure of the salt solution, which depends on the kind andconcentration of the salt solution and also the temperature. Since thevalues for various salts, regarding the above relations, are shown inchemical handbooks or the like, salts may be appropriately selecteddepending on the desired humidity.

The buffer 134 is formed with a plastic film or the like and is a bagvariable of volume. In the buffer 134, an induction opening 148introducing a flowing gas and a discharge opening 150 feeding out theinterior gas are provided in opposed positions. The induction opening148 is connected to the tube 146 from the humidity conditioner bottle136, and in conjunction therewith, the discharge opening 150 isconnected to the gas circulating portion 122 of the casing 118 so thatthe buffer 134 may be expanded depending upon the difference between thegas pressure introduced thereinto and the pressure of the ambient air tovary the volume thereof. Namely, when the internal pressure is elevated,the buffer 134 is expanded, and when the internal pressure is reduced,the buffer 134 is contracted, making the pressure difference between theinside and the outside to naturally be zero to enable circulationwithout causing variation of pressure of the gas.

Then, in the shown embodiment of the gas collecting system 10c, theopening 118a of the casing 118 is pressed onto the inspection object 80,and in conjunction therewith, the air pump 124 is driven. At this time,the packing 138 is provided on the opening 118a of the casing 118 tosealingly enclose the pressed portion by pressing on the surface of theinspection object 80. Further, since the casing 118 is formedtransparently, the set condition can be checked and the condition of thesurface of the inspection object 80 can be easily observed. Since thegas is sucked by the air pump 124, the gas within the casing 118 isintroduced into the impinger 128 causing bubbling in the collectingliquid 126 in the impinger 128, and passes therethrough to be suckedinto the air pump 124. The sucked gas is discharged from the dischargeportion 124b of the air pump 124, and is returned to the interior of thecasing 118 through the humidity conditioner bottle 136 and the buffer134 for circulation. At this time, the inspection objective gasdischarged from the inspection object 80 is captured in the collectingliquid 126 by bubbling through the collecting liquid 126 of the impinger128 from the inside of the enclosed casing. Then, the gas returned intothe casing 118 from the buffer 134 is purified, since the inspectionobjective gas is captured by the impinger 128. Also, the humiditythereof is also maintained constant by the humidity conditioner bottle136.

Thus, collection of the inspection objective gas is performed for apredetermined period of time by circulating the gas, and quantitativeanalysis is performed by chemical method to obtain the amount of theinspection objective gas contained in the collecting liquid 126 of theimpinger 128. At this time, the gas discharge amount can be derived bythe foregoing equation (1).

On the other hand, since the buffer 134 is disposed in the circulatingpassage of the gas around the casing 118, the pressure differencebetween the inside and the outside of the circulating passage can berestricted. By this, it becomes possible to prevent pressure variationin the casing 118 by pulsation of the air pump 124 and variation of theperipheral atmospheric temperature. Namely, generation of the pressuredifference due to pulsation of the air pump 124 and variation of theenvironmental temperature affects the increasing or decreasing of thepressure in respect of the inspection objective space, and causesleakage of the circulating gas to the outside or, converselyintroduction of the external air to cause error in measurement.Increasing and decreasing of pressure acts on the gas dischargingsurface of the inspection object 80 to disable measurement of thedischarged amount in natural condition. Such problem can be avoided bythe shown embodiment to enhance the precision of inspection of theinspection objective gas. Also, since the gas is circulated without itsvariation in the pressure, increasing or decreasing of pressure will notbe caused in the casing 118 so as to maintain satisfactory gas-tightseal between the casing 118 and the inspection object 80 to the extentof pressing through the packing 138.

Further, since the humidity conditioner bottle 136 is disposed in thecirculation passage of the gas around the casing 118, the humidity ofthe circulated gas can be maintained at a predetermined value by the useof equilibrium of water vapor pressure of the salt solution. For somekinds of materials of the inspection object 80 and some kinds of theinspection objective gases, humidity of the circulating gas causesvariation in the discharge amount of the inspection objective gas.However, this problem is prevented, and data quality is improved by theabove humidity conditioning.

Furthermore, since a system to circulate the gas including the casing118 is employed, the purified gas supply means, such as a purified gassupply device or a nitrogen gas supply device as an alternative becomesunnecessary. Due to this, the construction of the gas collecting system10c is made simple, compact and inexpensive.

On the other hand, the shown embodiment of the gas collecting system 10ccan perform not only inspection for the construction material, but alsocollection of the inspection objective gas from the material as it isused, namely at the arbitrary portion with respect to the building aftercompletion of construction, similar to the second and third embodimentof the gas collecting systems 10a and 10b.

On the other hand, the casing may, of course, be a box shaped chamberreceiving the inspection material piece as exemplified by the thirdembodiment.

In FIG. 17, a modification of the fourth embodiment is illustrated, inwhich a plurality of impingers 128 are provided for sequentiallymonitoring variation of the discharge amount of the inspection objectivegas according to elapsed time.

In the gas collecting system 10c shown in FIG. 17, a plurality of theimpingers 128 are provided in parallel, and the electromagnetic valves142 for switching connection are provided between these impingers 128and the casing 118, and the electromagnetic valve 142 is switched perevery predetermined collection period. Switching of the electromagneticvalve 142 may be automated by a timer control. The shown modification isconstructed so that connection of the impingers 128 is sequentiallyswitched. The shown gas collecting system 10c is suitable for inspectingthe discharge phenomenon of ammonia gas released from paint. Dischargeamount (discharge speed) of the ammonia gas varies according to elapsedtime from the time immediately after application of the paint tocompletion of curing. Therefore, by sequentially switching gascollection, it becomes possible to perform gas collection as timeelapses to monitor the process thereof.

Finally, discussion will be given for a simple analyzing method offormic aldehyde to be implemented using the shown embodiment of the gascollecting system 10. The members such as the impingers 14, which areconsumable articles to be exchanged, may be supplied as an analysis kit.

The analysis kit includes:

(i) 2N-KOH solution (aqueous sodium hydroxide having a normality of 2)is employed as the collecting liquid 28. Ten to twenty impingers 14respectively filled with 2.0 ml of this collecting liquid;

(ii) one Bial bottle A (having volume of 50 to 100 ml) containing AHMTreagent;

(iii) one Bial bottle (having volume of 50 to 100 ml) containing KIO₄reagent;

(iv) several plastic injectors (having volume of 1 ml);

(v) one impinger containing a standard color solution;

(vi) one sand glass (for 20 minutes); and

(vii) one portable absorptiometer.

Next, discussion will be given for operating procedure for measurementof concentration of formic aldehyde by employing the foregoing analysiskit.

(I) At first, the impinger 14 is mounted on the gas collecting system 10to suck the gas containing formic aldehyde. At this time, a standard gassuction amount of 3 liter and 10 minutes of standard required time areemployed.

(II) 0.5 ml of AHMT reagent is taken from the Bial bottle A by aninjector and added to the impinger 14. The impinger 14 is left in thiscondition for 15 to 20 minutes or longer. At this time, the sandglass isused.

(III) While the impinger 14 added with AHMT reagent is left, thestandard color solution is set in the absorptiometer. Then, a dial isadjusted so that the indication value becomes a predetermined value.

(IV) 0.5 ml of KIO₄ reagent is taken from the Bial bottle B by aninjector and added to the impinger 14.

(V) The impinger 14 is set in the absorptiometer to read the indicationvalue, and the read value is obtained as the concentration of formicaldehyde.

Accordingly, in the analysis method of formic aldehyde in connectionwith this embodiment, the impinger 14 used in the analysis kit (i) canefficiently collect formic aldehyde in the gas to enhance collectionefficiency by using 2N-KOH solution. Further, since the amount of thecollecting liquid to be used is small, such as 2.0 ml, high condensationcan be achieved even with small suction amount of the gas to facilitatedetection even in low gas concentration. This is an appropriateconcentration for certainly maintaining reaction ability of the AHMTreagent of (ii) which is added later, and it becomes unnecessary ofafter addition of alkali reagent.

On the other hand, AHMT reagent and KIO₄ reagent necessary for analysisare set with concentrations so that optimal reaction condition isobtained with respect to the collecting liquid 28 and so that the liquidamount to be added by the injector can be small. Namely, the compositionof the AHMT reagent is prepared to have a composition of AHMT: 1%, andHCl: 1 mol/liter, and the composition of the KIO₄ reagent is prepared tohave a composition of KIO₄ ; 1% and KOH: 0.25 N.

The additive amount of both reagents is set to be appropriate at 0.5 ml.This is because lower concentration than has been used conventionallyrequires about four times of additive amount, which lowers sensitivityof detection since color indication is lowered according to increase inoverall liquid amount. On the other hand, when additive amount of thereagent is extremely reduced, a reading error of the liquid amount uponmeasuring by the injector becomes large. In the shown embodiment, sincethe use amount of both reagents at one time is small as 0.5 ml, manyanalyses are possible even when the amounts of the reagents to becarried are small.

Further, both reagents are made as kits being contained in the Bialbottles A and B of (ii) and (iii). These Bial bottles are bottles withrubber caps, and the reagents can be metered and taken by the injectorwithout removing the caps. Therefore, the reagent may not be spilled ordeposited on the hand.

Next, the standard color solution shown in (v) is preliminarily preparedin a laboratory, by taking a standard colored liquid, which correspondsto a color indication density upon reaction of a known amount of formicaldehyde with the reagent, as the standard color solution, and byenclosing the liquid in the same container as the impinger 14.

By enclosing the standard color solution in the impinger 14, and byadjusting the color comparison meter (absorptiometer) by taking theabsorbance of the standard colored liquid as a standard for absorbancemeasurement, it becomes unnecessary to prepare an analytical curve byactually reacting the known amount of the formic aldehyde liquid uponeach analysis. Further, since the color indication density of the liquidindicating color by reacting formic aldehyde becomes unstable making thecolor gradually more pale according to elapsed time, the standardcolored liquid is prepared by using a red color dye having less fadingeffect.

On the other hand, since the color collecting system 10 has aconstruction which can constantly suck the predetermined amount of thegas, by adjusting the indication value of the absorptiometer to thepredetermined value by the standard colored liquid on the premise of thesuction gas amount, the indication value upon measurement of absorbanceof an unknown sample can be directly read as the concentration of theformic aldehyde. Accordingly, calculation using molecular amount offormic aldehyde and a volume conversion coefficient or so forth becomesunnecessary. Also, a compact, lightweight and portable absorptiometeroperated by dry cells is used, and it has a permselective filter ofwavelength 530 nm.

Accordingly, in the shown embodiment, by employing the impinger 14, theAHMT reagent, KIO₄ reagent, the injector, the standard color solution,the sand glass and the portable absorptiometer formed as a kit, formicaldehyde concentration is measured by sucking the gas by the gascollecting system 10. Therefore, the system can be made compact to beeasily handled and requires no special device. Thus, a result can beobtained within a short period and exactly at the place where the gas iscollected. Further, expert knowledge and chemical calculation becomesunnecessary, and also, transferring or division of the sampled solutionbecomes unnecessary and requires no special measuring equipment such aswhole pipette or the like for chemical analysis, which requires skill inhandling.

The solution of the collecting liquid 28 and the reagents can be takenout by the injector without releasing the cap. Therefore, even if thebottleturns over, the content will never be spilled, which enables safeoperation. Further, since analysis can be performed at the gas samplingsite, it becomes unnecessary to pay any attention to transportation ofthe sample. Also, it becomes unnecessary to ask analysis for an externalanalyzing organization requiring high cost. Since result can be obtainedat low cost, many measurements can be performed one by one as checkingeach test result.

As set forth above, in the shown embodiment of the formic aldehydeanalyzing method, the measurement of concentration of formic aldehyderequires no expert knowledge, and can be carried out easily by simpleoperations at low cost and within a short period at the exact place.Therefore, even when inspection is performed within a new building, alarge amount of inspection data, such as how much formic aldehyde isgenerated from which construction material and how much formic aldehydeis present in the room environment, can be obtained, easily.

In other embodiment of the formic aldehyde analyzing method, theanalyzing kit is provided with:

(i) 2N-KOH solution (aqueous sodium hydroxide having a normality of 2)is employed as the collecting liquid 28. Ten to twenty impingers 14respectively filled with 2.0 ml of this collecting liquid 28;

(ii) one Bial bottle A (having volume of 50 to 100 ml) containing AHMTreagent prepared by using HClO₄ ;

(iii) one Bial bottle B (having volume of 50 to 100 ml) containing KIO₄reagent;

(iv) several plastic injectors (having volume of 1 ml);

(v) one impinger containing a standard color solution;

(vi) one sand glass (for 20 minutes); and

(vii) one portable absorptiometer.

On the other hand, the concentrations of the AHMT reagent and KIO₄reagent necessary for analysis are set so that optimal reactingcondition with respect to the collecting liquid 28 can be obtained, andthe liquid amount to be added by the injector can be small. Namely, thecomposition of AHMT reagent used is AHMT: 1% and HClO₄ : 4 to 5%, andthe composition of KIO₄ reagent used is KIO₄ : 1% and KOH: 0.2 to 0.3 N.

The operation procedure for measuring formic aldehyde concentration bymeans of this analysis kit is the same as that of the former kit.

On the other hand, in the shown embodiment, concerning the collectingliquid 28 and the AHMT reagent, the following matters are considered.Since the AHMT reagent cannot be dissolved without adding acid, HCl isnormally added thereto upon dissolving this reagent. Upon handling thisreagent, the reagent is sampled by the injector as set forth above inorder to improve operability. However, considering repeated sampling ofthe HCl-added AHMT reagent by the injector, corrosion should be causedon the injection needle because of HCl. Thus, the duration of the needleis considered to be quite short. Also, the reagent may be contaminatedby eluted substance from the needle, such as iron ion generated bycorrosion of the needle, which possibly causes error in analysis.Therefore, in the shown embodiment, for dissolving the AHMT reagent,HClO₄ is used in place of HCl. By this, corrosion of the injectionneedle and contamination of reagent can be avoided. On the other hand,2N-KOH (potassium hydroxide solution having a normality of 2) may beemployed as the collecting liquid 28 in addition to the foregoing2N-NaOH. However, when HClO₄ is employed in AHMT reagent and when 2N-KOHis employed as the collecting liquid, potassium perchlorate, which ishardly water-soluble, is formed by reaction of HClO₄ and KOH when AHMTreagent is added to the collecting liquid 28, causing white turbidity inthe sample solution. Therefore, considering that HClO₄ is used for AHMTreagent, 2N-NaOH is employed as the collecting liquid 28.

In either analyzing method, AHMT reagent is added to the collectingliquid 28 after gas collecting operation, and subsequently, KIO₄ reagentis added. An embodiment of an analyzing method of formic aldehyde whichcan further simplify the analyzing method will be discussed.

In this case, analyzing kit is provided with:

(i) ten to twenty impingers normally filled with 2 to 3 ml of thecollecting liquid 28;

(ii) one impinger containing the standard color solution;

(iii) several plastic injectors (having volume of 1 ml); and

(iv) one portable absorptiometer.

Particularly, the shown embodiment is designed to eliminate theoperation for adding reagents after completing the collection, andwaiting time of the reaction process. Therefore, in the shownembodiment, the collecting liquid 28 is prepared by mixing an alkalireagent and a reducing reagent, such as sodium hyposulfite and so forth,at an appropriate mixing ratio. In the conventional method, three kindsof reagents, which are the alkali reagent, the AHMT reagent, and KIO₄reagent are used separately. In this case, when these reagents arepreliminarily mixed, normal reaction with formic aldehyde cannot becaused. Therefore, it becomes necessary to add them separately in thepredetermined sequential order and by keeping time interval required forreaction.

In contrast, when the collecting agent 28 of the shown embodiment isemployed, it becomes possible to add AHMT liquid to the collectingliquid 28 before gas collecting operation, and KIO₄ reagent becomesunnecessary.

Then, since the AHMT reagent can be added in advance, color indicationreaction can be carried out along with gas collection, and gascollecting operation can be performed by visually monitoring thecondition thereof. Since color indication reaction progresses inconjunction with gas collection, it becomes possible to omit the periodof time for waiting for reaction by adding AHMT reagent after gascollection. Furthermore, KIO₄ reagent is required for generating a redcolored substance by oxidizing the reactive intermediate product of AHMTreagent and formic aldehyde. Since AHMT reagent can be added in advance,oxygen in the air introduced into the collecting liquid 28 during theprocess of gas collection may serve as oxidation agent, in the place ofKIO₄ reagent. As a result, KIO₄ reagent becomes unnecessary. Next,operation procedure in measurement of formic aldehyde concentrationusing this analyzing kit will be discussed hereinafter.

In this case, the procedure is quite simple:

(I) 0.5 ml of AHMT solution is added by the injector to the impinger 14containing the collecting liquid 28, and gas is sucked. At this time, 3liters of gas suction amount is taken as a standard, and about 10minutes is taken as the reference necessary period of time.

(II) The indication value is read by setting the impinger 14 to theabsorptiometer, and the read value is obtained as formic aldehydeconcentration.

Namely, in the shown embodiment, a given amount of collecting liquid 28,prepared by mixing the alkali reagent and the reducing reagent, such assodium hyposulfite and so forth, at an appropriate mixing ratio, isfilled in the impinger 14. Then, the given amount of the air in theinspection objective space is passed through the impinger 14. Inconjunction therewith, the standard color solution is set in theabsorptiometer for adjustment, so that the indication value equals tothe predetermined value. Then, the impinger 14 is set in theabsorptiometer, and analysis is made by detecting formic aldehydeconcentration from the indication value.

What is claimed is:
 1. A gas collecting system comprising:a portable airpump which is driven by a portable battery to suck a gas in aninspection objective space; a collection vessel, in which a collectingliquid for collecting an inspection objective gas from said gas isfilled; an induction passage having one end connected to said collectionvessel and the other end communicated with said inspection objectivespace for introducing said gas into said collection vessel; a suctionpassage having one end connected to said collection vessel and the otherend connected to a suction port of said air pump for introducing saidgas in said collection vessel into said air pump; an accumulation bodyconnected to a discharge port of said air pump, accumulating said gasdischarged from said air pump and serving as a volumeter; drying meansdisposed between said accumulation body and said collection vessel fordrying said gas; a pressure switch detecting an internal pressure ofsaid accumulation body; a bypass passage connecting said accumulationbody to said suction port of said air pump bypassing said collectionvessel; and switching means for switching a flow path connecting saidaccumulation body to either one of said discharge port of said air pumpand said bypass passage, and in conjunction therewith, connecting saiddischarge port of said air pump to an ambient air opening passage whensaid accumulation body is connected to said bypass passage.
 2. A gascollecting system as set forth in claim 1, which includes a mainreceptacle box and an auxiliary receptacle box mounted on said mainreceptacle box,said main receptacle box receives said air pump and saidbattery therein and has mounting surfaces for mounting said drying meansand said collection vessel, said auxiliary receptacle box receives saidswitching means and said pressure switch therein, and has a mountingportion for detachably mounting said accumulation body.
 3. A gascollecting system as set forth in claim 1, wherein said accumulationbody is a foldable and exchangeable bag.
 4. A gas collecting system asset forth in claim 3, wherein said bag is a vinyl bag.
 5. A gascollecting system as set forth in claim 1, wherein said collectionvessel is formed with transparent material to be used as a colorcomparison tube, and is also used as a reaction tube to be filled withreagents reacting with said inspection objective gas.
 6. A gascollecting system as set forth in claim 1, wherein said pressure switchdetects an internal pressure of said accumulation body reaching apredetermined pressure to output a stop signal for said air pump.
 7. Agas collecting system as set forth in claim 1, wherein said pressureswitch is connected among said air pump, a buzzer and a power sourcesupplying operation power to said air pump and said buzzer, saidpressure switch being constructed with a bag-formed extending membercommunicated with said accumulation body and causing expanding andcontracting deformation by a pressure of said gas introduced from saidaccumulation body, a cylindrical guide surrounding said extending memberto guide said extending member in expanding direction, and a switch mainbody being provided in opposition to said extending member in expandingdirection thereof and being depressed by said expanding member forselectively establishing connection between a common terminal and eitherone of two switching terminals, wherein,each of said switching terminalsis connected to said buzzer and said air pump, respectively, and saidcommon terminal is connected to said power source, and when an internalpressure of said accumulation body is reached to a predeterminedpressure, the connection with said common terminal is switched from saidswitching terminal of said air pump to said switching terminal of saidbuzzer by said extending member expanded in response thereto.
 8. A gascollecting system as set forth in claim 1, wherein at least one of saidinduction passage and said suction passage has a capillary portion.
 9. Agas collecting system as set forth in claim 1, wherein said collectionvessel is formed into a cylindrical shape and its opening portion isclosed by a cap, and said induction passage and said suction passagehave an injection needle form tube portion, respectively, these tubeportions being inserted into said collection vessel through said cap.10. A gas collecting system as set forth in claim 9, wherein at least aportion of said cap covering said opening portion of said collectionvessel is coated with an insulation layer of a material not influencingsaid collecting liquid.
 11. A gas collecting system as set forth inclaim 9, wherein said injection needle form tube portion is closed at atip end thereof and is formed with a laterally oriented communicationopening in the vicinity of said tip end portion.
 12. A gas collectingsystem as set forth in claim 1, wherein said switching means isconnected to a speed adjusting switch controlling driving speed of saidair pump by varying a supply voltage to said air pump from said batteryin response to switching operation of said flow path, when saiddischarge port of said air pump is connected to said accumulation body,said air pump is driven at low speed, and when said bypass passage isconnected to said accumulation body, said air pump is driven at highspeed.
 13. A gas collecting system as set forth in claim 1, wherein acheck valve is provided on the upstream side of said suction port ofsaid air pump to only allow said gas flow to said suction port.
 14. Agas collecting system as set forth in claim 1, wherein a given amount of2N-NaOH solution as said collecting liquid is filled in said collectionvessel, after passing a given amount of said gas containing saidinspection objective gas, a given amount of AHMT reagent prepared byusing HClO₄ as said reagents is filled within said collection vessel toleave for a given period, and in conjunction with, an indication valueis adjusted to a predetermined value by setting a standard colorsolution in an absorptiometer, then, a given amount of KIO₄ reagent assaid reagents is added into said collection vessel, and then, saidcollection vessel is set in said absorptiometer for detectingconcentration of formic aldehyde from the indication value thereof. 15.A gas collecting system as set forth in claim 1, wherein a given amountof 2N-KOH solution as said collecting liquid is filled in saidcollection vessel, after passing a given amount of said gas containingsaid inspection objective gas, a given amount of AHMT reagent as saidreagents is filled within said collection vessel to leave for a givenperiod, and in conjunction with, an indication value is adjusted to apredetermined value by setting a standard color solution in anabsorptiometer, then, a given amount of KIO₄ reagent as said reagents isadded into said collection vessel, and then said collection vessel isset in said absorptiometer for detecting concentration of formicaldehyde from the indication value thereof.
 16. A gas collecting systemcomprising:a portable air pump which is driven by a portable battery tosuck a gas in an inspection objective space; a collection vessel, inwhich a collecting liquid for collecting an inspection objective gasfrom said gas is filled; an induction passage having one end connectedto said collection vessel and the other end communicated with saidinspection objective space for introducing said gas into said collectionvessel; a suction passage having one end connected to said collectionvessel and the other end connected to a suction port of said air pumpfor introducing said gas in said collection vessel into said air pump;an accumulation body connected to a discharge port of said air pump,accumulating said gas discharged from said air pump and serving as avolumeter; drying means disposed between said accumulation body and saidcollection vessel for drying said gas; a pressure switch detecting aninternal pressure of said accumulation body; a bypass passage connectingsaid accumulation body to said suction port of said air pump bypassingsaid collection vessel; switching means for switching a flow pathconnecting said accumulation body to either one of said discharge portof said air pump and said bypass passage, and in conjunction therewith,connecting said discharge port of said air pump to an ambient airopening passage when said accumulation body is connected to said bypasspassage; a main receptacle box receiving said air pump and said batterytherein and having mounting surfaces for mounting said drying means andsaid collection vessel; and an auxiliary receptacle box mounted on saidmain receptacle box, receiving said switching means and said pressureswitch therein, and having a mounting portion for detachably mountingsaid accumulation body, wherein,said collection vessel is formed of atransparent material to be used as a color comparison tube, and is alsoused as a reaction tube filled with reagents reacting with saidinspection objective gas, said pressure switch detects an internalpressure of said accumulation body reaching a predetermined pressure foroutputting a stop signal of said air pump, and said accumulation body isa foldable and exchangeable bag.
 17. A gas collecting system as setforth in claim 1, which further comprises:a casing covering saidinspection objective space in a sealing condition from outside toenclose said inspection objective gas discharged from an inspectionobject enclosed therein; a sampling port provided with said casing, andconnected to said induction passage for introducing said gas containingsaid inspection objective gas in said casing into said collectionvessel; a supply port provided with said casing for supplying areference gas into said casing depending upon suction of said gas insaid casing by said air pump, and a capillary passage disposed betweensaid sampling port and said accumulation body for lowering flow velocityof said gas sucked.
 18. A gas collecting system as set forth in claim17, wherein said casing has an opening in a bottom portion where apacking fitting said casing with said inspection object in gas-tightfashion is provided.
 19. A gas collecting system as set forth in claim17, wherein said casing is a chamber receiving a material piece to beinspected as said inspection object.
 20. A gas collecting system as setforth in claim 17, wherein said casing is formed of a transparentmaterial.
 21. A gas collecting system as set forth in claim 17, whereinsaid capillary passage is disposed between said sampling port and saidcollection vessel.
 22. A gas collecting system as set forth in claim 17,wherein a filter is connected to said supply port, and said referencegas is an ambient air purified by said filter.
 23. A gas collectingsystem as set forth in claim 17, wherein a reference gas receptacle bodyfilled with said reference gas is connected to said supply port, andsaid reference gas is supplied to said casing from said reference gasreceptacle body.
 24. A gas collecting system as set forth in claim 17, astirring means is provided in said casing to stir said gas therein. 25.A gas collecting system comprising:a casing covering an inspectionobjective space in a sealing condition from outside to enclose aninspection objective gas discharged from an inspection object enclosedtherein; a sampling port provided with said casing to sample a gascontaining said inspection objective gas in said casing; an air pumpsucking said gas from said inspection objective space in said casing; asupply port provided with said casing for supplying a reference gas intosaid casing depending upon suction of said gas in said casing by saidair pump; a collection vessel, in which a collection liquid forcollecting said inspection objective gas from said gas is filled; aninduction passage having one end connected to said collection vessel andthe other end connected to said sampling port for introducing said gasinto said collection vessel; a suction passage having one end connectedto said collection vessel and the other end connected to a suction portof said air pump for introducing said gas in said collection vessel intosaid air pump; an accumulation body connected to a discharge port ofsaid air pump, accumulating said gas discharged from said air pump andserving as a volumeter; a capillary passage disposed between saidsampling port and said accumulation body for lowering flow velocity ofsaid gas sucked; drying means disposed between said accumulation bodyand said collection vessel for drying said gas; a pressure switchdetecting an internal pressure of said accumulation body; a bypasspassage connecting said accumulation body to said suction port of saidair pump bypassing said collection vessel; and switching means forswitching a flow path connecting said accumulation body to either one ofsaid discharge port of said air pump and said bypass passage, and inconjunction therewith, connecting said discharge port of said air pumpto an ambient air opening passage when said accumulation body isconnected to said bypass passage, wherein,said casing has an opening ina bottom portion, on which a packing for fitting said casing with saidinspection object in gas-tight fashion is provided, a filter isconnected to said supply port, and said reference gas is an ambient airpurified by said filter.
 26. A gas collecting system as set forth inclaim 1, which further comprises:a casing covering said inspectionobjective space in a sealing condition from outside to enclose saidinspection objective gas discharged from an inspection object enclosedtherein; a sampling port provided with said casing, and connected tosaid induction passage for introducing said gas containing saidinspection objective gas in said casing into said collection vessel; aninternal pressure maintaining bag provided in said casing and havingexpandability and sealing ability; and a pressure induction passageconnected to said internal pressure maintaining bag through said casingand introducing a pressure adjusting gas for expanding said internalpressure maintaining bag according to lowering of the internal pressureof said casing.
 27. A gas collecting system as set forth in claim 26,wherein said casing has an opening in a bottom portion, and a packingfor fitting said casing with said inspection object in gas-tight fashionis provided on said opening.
 28. A gas collecting system as set forth inclaim 26, wherein said casing is a chamber receiving a material piece tobe inspected as said inspection object.
 29. A gas collecting system asset forth in claim 26, wherein said casing is formed of a transparentmaterial.
 30. A gas collecting system as set forth in claim 26, astirring means is provided in said casing and said stirring means stirssaid gas in said casing.
 31. A gas collecting system as set forth inclaim 26, wherein said pressure adjusting gas is introduced through saidpressure induction passage into said internal pressure maintaining bagby a pressure reduction in said casing.
 32. A gas collecting system asset forth in claim 26, wherein a port opening and closing means isdisposed between said sampling port and said induction passage foropening and closing therebetween, and a pressure introducing means foropening and closing said pressure introducing passage is providedtherewith.
 33. A gas collecting system as set forth in claim 26, whichfurther comprises:a volume varying bag provided in said casing andhaving expandability and sealing ability, and a gas supplying anddischarging passage connected to said volume varying bag through saidcasing, for supplying and discharging a volume adjusting gas to saidvolume varying bag to vary volume in said casing by expanding anddeflating said volume varying bag.
 34. A gas collecting system as setforth in claim 33, wherein at least either one of said internal pressuremaintaining bag and said volume varying bag is disposed in plural insaid casing.
 35. A gas collecting system as set forth in claim 33,wherein an opening and closing means for said gas supplying anddischarging passage is provided therewith.
 36. A gas collecting systemas set forth in claim 33, wherein an adjusting gas receptacle bodyfilled with said pressure adjusting gas or said volume adjusting gas isconnected to at least either one of said pressure induction passage andsaid gas supplying and discharging passage, and these gas are suppliedfrom said adjusting gas receptacle body.
 37. A gas collecting systemcomprising:a casing covering an inspection objective space in a sealingcondition from outside to enclose an inspection objective gas dischargedfrom an inspection object enclosed therein; a sampling port providedwith said casing to sample a gas containing said inspection objectivegas in said casing; an air pump sucking said gas from said inspectionobjective space in said casing; a collection vessel filled with acollecting liquid for collecting said inspection objective gas from saidgas; an induction passage having one end connected to said collectionvessel and the other end connected to said sampling port for introducingsaid gas into said collection vessel; a suction passage having one endconnected to said collection vessel and the other end connected to asuction port of said air pump for introducing said gas in saidcollection vessel into said air pump; an accumulation body connected toa discharge port of said air pump, accumulating said gas discharged fromsaid air pump and serving as a volumeter; drying means disposed betweensaid accumulation body and said collection vessel for drying said gas; apressure switch detecting an internal pressure of said accumulationbody; a bypass passage connecting said accumulation body to said suctionport of said air pump bypassing said collection vessel; switching meansfor switching a flow path connecting said accumulation body to eitherone of said discharge port of said air pump and said bypass passage, andin conjunction therewith, connecting said discharge port of said airpump to an ambient air opening passage when said accumulation body isconnected to said bypass passage; an internal pressure maintaining bagprovided in said casing and having expandability and sealing ability; apressure induction passage connected to said internal pressuremaintaining bag through said casing and introducing a pressure adjustinggas for expanding said internal pressure maintaining bag according tolowering of the internal pressure of said casing; a volume varying bagprovided in said casing and having expandability and sealing ability;and a gas supplying and discharging passage connected to said volumevarying bag through said casing, for supplying and discharging a volumeadjusting gas to said volume varying bag for varying volume in saidcasing by expanding and deflecting said volume varying bag.
 38. A gascollecting system comprising:a casing covering an inspection objectivespace in a sealing condition from outside to enclose an inspectionobjective gas discharged from an inspection object enclosed therein; apair of gas circulating ports provided with said casing and circulatinga gas through said casing; an air pump sucking said gas containing saidinspection objective gas from said inspection objective space in saidcasing; a collection vessel, in which a collection liquid collectingsaid inspection objective gas from said gas is filled; an inductionpassage having one end connected to said collection vessel and the otherend connected to one of said gas circulating ports of said casing forintroducing said gas into said collection vessel; a suction passagehaving one end connected to said collection vessel and the other endconnected to a suction port of said air pump for introducing said gas insaid collection vessel into said air pump; a buffer disposed between adischarge port of said air pump and the other of said gas circulatingports of said casing to buffer a gas pressure by temporarily storingsaid gas discharged from said air pump, and in conjunction therewith, tocirculate said gas to said casing again; and humidity adjusting meansdisposed between said buffer and said collection vessel for adjusting ahumidity of said gas circulated to be constant.
 39. A gas collectingsystem as set forth in claim 38, wherein said casing has an opening in abottom portion, and a packing for fitting said casing with saidinspection object in gas-tight fashion is provided on said opening. 40.A gas collecting system as set forth in claim 38, wherein said casing isa chamber receiving a material piece to be inspected as said inspectionobject.
 41. A gas collecting system as set forth in claim 38, whereinsaid casing is formed of a transparent material.
 42. A gas collectingsystem as set forth in claim 38, wherein said buffer is a bag to beexpanded and deflected depending upon a difference between a pressure ofsaid gas stored therein and an ambient air pressure.
 43. A gascollecting system as set forth in claim 38, wherein said humidityadjusting means is a container filled with a humidity adjusting liquidadjusting humidity of said gas.
 44. A gas collecting system as set forthin claim 43, wherein said humidity adjusting liquid is a salt solution.45. A gas collecting system as set forth in claim 38, wherein saidcollection vessel is provided in plural and in parallel, and switchingdevice disposed between said collection vessels and one of said gascirculating ports of said casing to selectively communicate said casingwith either one of said collection vessels.
 46. A gas collecting systemas set forth in claim 45, wherein said switching device switches thecommunication between said respective collection vessels and said casingaccording to a lapsed time.
 47. A gas collecting system as set forth inclaim 46, wherein said switching device is controlled the switchingoperation by means of a timer.
 48. A gas collecting system as set forthin claim 38, wherein said air pump is portable and is driven by aportable battery.
 49. A gas collecting system as set forth in claim 38,wherein said collection vessel is formed with transparent material to beused as a color comparison tube, and is also used as a reaction tube tobe filled with reagents reacting with said inspection objective gas. 50.A gas collecting system as set forth in claim 38, wherein saidcollection vessel is formed into a cylindrical shape and its openingportion is closed by a cap, and said induction passage and said suctionpassage having an injection needle form tube portion, respectively,these tube portions being inserted into said collection vessel throughsaid cap.
 51. A gas collecting system as set forth in claim 50, whereinsaid cap is coated with an insulation layer of a material notinfluencing said collecting liquid at least at a portion covering saidopening portion of said collection vessel.
 52. A gas collecting systemas set forth in claim 38, wherein a given amount of 2N-NaOH solution assaid collecting liquid is filled in said collection vessel, afterpassing a given amount of said gas containing said inspection objectivegas, a given amount of AHMT reagent prepared by using HClO₄ as saidreagents is filled within said collection vessel to leave for a givenperiod, and in conjunction therewith, an indication value is adjusted toa predetermined value by setting a standard color solution in anabsorptiometer, then, a given amount of KIO₄ reagent as said reagents isadded into said collection vessel, and then, said collection vessel isset in said absorptiometer for detecting concentration of formicaldehyde from the indication value thereof.
 53. A gas collecting systemas set forth in claim 38, wherein a given amount of 2N-KOH solution assaid collecting liquid is filled in said collection vessel, afterpassing a given amount of said gas containing said inspection objectivegas, a given amount of AHMT reagent as said reagents is filled withinsaid collection vessel to leave for a given period, and in conjunctionwith, an indication value is adjusted to a predetermined value bysetting a standard color solution in an absorptiometer, then, a givenamount of KIO₄ reagent as said reagents is added into said collectionvessel, and then, said collection vessel is set in said absorptiometerfor detecting concentration of formic aldehyde from the indication valuethereof.
 54. A gas collecting system comprising:a casing covering aninspection objective space in a sealing condition from outside toenclose an inspection objective gas discharged from an inspection objectenclosed therein; a pair of gas circulating ports provided with saidcasing to circulate a gas through said casing; an air pump sucking saidgas containing said inspection objective gas from said inspectionobjective space in said casing; a collection vessel filled with acollection liquid for collecting said inspection objective gas from saidgas; an induction passage having one end connected to said collectionvessel and the other end connected to one of said gas circulating portsof said casing for introducing said gas into said collection vessel; asuction passage having one end connected to said collection vessel andthe other end connected to a suction port of said air pump forintroducing said gas in said collection vessel into said air pump; abuffer disposed between a discharge port of said air pump and the otherof said gas circulating ports of said casing to buffer a gas pressure bytemporarily storing said gas discharged from said air pump, and inconjunction therewith, to supply said gas to said casing again; andhumidity adjusting means disposed between said buffer and saidcollection vessel for adjusting a humidity of said gas circulated to beconstant, whereinsaid casing has an opening in a bottom portion, onwhich a packing for fitting said casing with said inspection object ingas-tight fashion is provided, said collection vessel is formed withtransparent material to be used as a color comparison tube, and is alsoused as a reaction tube to be filled with reagents reacting with saidinspection objective gas, said buffer is a bag to be expanded anddeflected depending upon a difference between a pressure of said gasstored therein and an ambient air pressure, and said humidity adjustingmeans is a container filled with a humidity adjusting liquid prepared bya salt solution for adjusting humidity of said gas.
 55. A gas collectingsystem comprising:a casing covering an inspection objective space in asealing condition from outside to enclose an inspection objective gasdischarged from an inspection object enclosed therein; a pair of gascirculating ports provided with said casing and circulating a gasthrough said casing; an air pump sucking said gas containing saidinspection objective gas from said inspection objective space in saidcasing; a collection vessel filled with a collection liquid collectingsaid inspection objective gas from said gas; an induction passage havingone end connected to said collection vessel and the other end connectedto one of said gas circulating ports of said casing for introducing saidgas into said collection vessel; a suction passage having one endconnected to said collection vessel and the other end connected to asuction port of said air pump for introducing said gas in saidcollection vessel into said air pump; a buffer disposed between adischarge port of said air pump and the other of said gas circulatingports of said casing to buffer a gas pressure by temporarily storingsaid gas discharged from said air pump, and in conjunction therewith, tocirculate said gas to said casing again; and humidity adjusting meansdisposed between said buffer and said collection vessel for adjusting ahumidity of said gas circulated to be constant, whereinsaid casing hasan opening in a bottom portion, on which a packing for fitting saidcasing with said inspection object in gas-tight fashion is provided,said buffer is a bag to be expanded and deflected depending upon adifference between a pressure of said gas stored therein and an ambientair pressure, said humidity adjusting means is a container filled with ahumidity adjusting liquid prepared by a salt solution for adjustinghumidity of said gas,said collection vessel is provided in plural and inparallel, said collection vessels being formed with transparent materialto be used as a color comparison tube, and being also used as a reactiontube to be filled with reagents reacting with said inspection objectivegas, and switching device is disposed between said collection vesselsand one of said gas circulating ports of said casing to selectivelycommunicate said casing with either one of said collection vesselsaccording to time counted.